Article directory

introduction
1. What is a statement?
Two, branch statement
Three, loop statement
Summarize

introduction

In programming, we need to let the program make choices according to different situations and perform certain tasks repeatedly . The branching and looping constructs of the C language provide powerful tools for achieving these goals. ifThis article will explore the branch (such as and switch) and loop (such as while, forand ) structures in C language do...whileto help you understand how to control the flow and logic of the program more effectively. Whether you are a beginner or an experienced developer, this knowledge will add value to your programming journey.

1. What is a statement?

In programming, statements are one of the basic elements that make up a program, and they represent instructions or operations that the computer needs to perform . A statement is the unit of operation in a program. By combining different types of statements, we can build complex program logic and functions. In C language, statements can be divided into many types, including expression statements , assignment statements , conditional statements, etc., and each type has its specific function and usage.

Let's look at some examples of common C language statements to better understand the concept of statements:

1.1 Expression statement

An expression is a calculation formula composed of operators, operands, and function calls. Expression statements are usually used to perform some calculation operations, but its results are usually not used.

For example:

x = y + z;    // 赋值表达式
result = a * b + c;    // 数学表达式

1.2 Assignment statement

Assignment statements are used to assign a value to a variable, thereby updating the contents of the variable. This is often used in programs to store data and compute results.

For example:

num = 10;    // 将值10赋给变量num
total = total + price;    // 将total和price的和赋给total

1.3 Function call statement

A function is a predefined block of code, and through a function call statement, we can perform operations within the function. Function call statements are usually used to complete specific tasks, such as input and output, mathematical calculations, and so on.

For example:

printf("Hello, world!");    // 调用printf函数输出文本
scanf("%d", &value);    // 调用scanf函数读取用户输入的整数

1.4 Compound Statements

A compound statement is a group of {}statements enclosed in curly braces ( ) that are treated as a unit. Compound statements can contain multiple types of statements and are used to organize and control the execution of code.

For example:

{
    
    
    int x = 5;
    printf("The value of x is %d\n", x);
}

1.5 Empty statement

An empty statement is a statement that does not contain any operations, and it is usually used when the syntax requires a statement but no actual operation. An empty statement contains only a semicolon.

For example:

;    // 空语句

1.6 Control Statements

Control statements are key tools in programming, used to manage the flow of program execution and implement different program structures. In C language, control statements are divided into three categories:

Conditional judgment statement (branch statement) : This type of statement allows different execution paths to be selected according to different conditions. These include:
- if statement : Executes a code block based on a condition, and can contain a elseblock for handling conditions that are not met.
- Switch statement : Jump to different casebranches based on the value of the expression, which can realize the selection of multiple conditions.
Loop execution statement : This type of statement allows a piece of code to be executed repeatedly until a certain condition is met. include:
- do while statement : Execute the code block once, and then execute it repeatedly according to the condition.
- while statement : Before the loop starts, it is judged whether the condition is satisfied, and if it is satisfied, the code in the loop body is executed.
- for statement : Initialize the counter before the loop starts, and execute the code block repeatedly according to the condition and update rules.
Go to statement : This type of statement is used to control the jump of the program. include:
- break statement : In a loop or switch statement, terminate the loop early or jump out of the switch.
- continue statement : Skip the remainder of the current loop iteration and go to the next iteration.
- return statement : Returns a value from a function and terminates the execution of the function.
- goto statement : Although deprecated, it can unconditionally jump to a label location in the code.

This article focuses on control statements.

Each statement ;ends with a semicolon ( ) to signify the end of the statement. Proper use of semicolons is very important when writing programs because they tell the compiler when one statement ends and the next begins.

Two, branch statement

Branch statement is one of the important control structures in C language, which allows the program to choose different execution paths according to different conditions. With branch statements, you can implement conditional program execution, making programs more intelligent and flexible . Branch statements in C language mainly include ifstatements and switchstatements.

2.1 `if`Statement

In the C language, ifa statement is an important conditional judgment statement , which allows different code blocks to be executed according to the true or false condition , thereby realizing conditional program execution. ifThe flexibility of the statement allows us to choose different program paths according to different situations, making the program more intelligent and logical.

2.1.1 Basic syntax

ifThe basic syntax of the statement is as follows:

if (条件) {
    
    
    // 如果条件为真，执行这里的代码
}

条件is a Boolean expression or an expression that evaluates to a Boolean value. If the condition evaluates to true (non-zero), execute the code block inside the curly braces; if the condition evaluates to false (zero), skip this code block and continue to execute the subsequent code.

Here is a simple example showing how to use ifthe statement:

#include <stdio.h>

int main() {
    
    
    int num;

    printf("Enter an integer: ");
    scanf("%d", &num);

    if (num > 0) {
    
    
        printf("%d is positive.\n", num);
    }

    printf("Program finished.\n");
    return 0;
}

In this example, the user is asked to enter an integer. The program uses ifthe statement to check whether the integer entered is a positive number. If it is a positive number (that is, the condition num > 0is true), then output the corresponding information; otherwise, directly skip the output part and continue to execute the subsequent code.

2.1.2 Using `else`Statements

In addition to basic ifstatements, you can also use elseto specify another block of code to execute when the condition is not met:

#include <stdio.h>

int main() {
    
    
    int num;

    printf("Enter an integer: ");
    scanf("%d", &num);

    if (num > 0) {
    
    
        printf("%d is positive.\n", num);
    } else {
    
    
        printf("%d is not positive.\n", num);
    }

    printf("Program finished.\n");
    return 0;
}

In this example, according to the integer entered by the user, the program will output the corresponding information, either positive or not. elseStatements enable you to choose between two different possibilities.

2.1.3 Nested if statements

You can also ifnest one statement inside another ifto handle more complex conditional cases:

#include <stdio.h>

int main() {
    
    
    int num;

    printf("Enter an integer: ");
    scanf("%d", &num);

    if (num > 0) {
    
    
        printf("%d is positive.\n", num);
    } else {
    
    
        if (num < 0) {
    
    
            printf("%d is negative.\n", num);
        } else {
    
    
            printf("%d is zero.\n", num);
        }
    }

    printf("Program finished.\n");
    return 0;
}

In this example, depending on the integer entered by the user, the program will output a positive, negative, or zero message. This makes use of nested ifstatements to handle different situations.

2.1.4 Multi-layer `if-else`statements

In actual programming, it is often encountered that multiple conditions need to be judged at the same time . To handle such complex situations, you can use multiple layers of if-elsestatements to implement different operations under different conditions. Multi-layer if-elsestatements can effectively combine and nest conditional judgments to handle multiple conditions.

The basic syntax of a multi-level if-elsestatement is as follows:

if (条件1) {
    
    
    // 条件1为真时执行的代码
} else if (条件2) {
    
    
    // 条件2为真时执行的代码
} else if (条件3) {
    
    
    // 条件3为真时执行的代码
} else {
    
    
    // 所有条件均不满足时执行的代码
}

**This structure allows you to judge one by one according to multiple conditions until you find the first branch that meets the conditions, and then execute the corresponding code block. ** If all conditions are not met, the last elseblock of code will be executed.

The following example demonstrates if-elsethe use of multilevel statements:

#include <stdio.h>

int main() {
    
    
    int score;

    printf("Enter your score: ");
    scanf("%d", &score);

    if (score >= 90) {
    
    
        printf("Grade: A\n");
    } else if (score >= 80) {
    
    
        printf("Grade: B\n");
    } else if (score >= 70) {
    
    
        printf("Grade: C\n");
    } else if (score >= 60) {
    
    
        printf("Grade: D\n");
    } else {
    
    
        printf("Grade: F\n");
    }

    return 0;
}

In this example, according to the score entered by the user, the program uses multi-layer if-elsestatements to determine the score segment it is in, and outputs the corresponding grade. Depending on the score, the program will choose to execute in different conditional branches.

Multi-layer if-elsestatements can clearly express the logic of multiple conditional judgments, making the program structure more intuitive and easy to understand. When you need to handle multiple conditions, combining multiple if-elsebranches together can effectively build complex program logic.

ifStatements are an important tool for achieving conditional program execution. Whether it is input verification or multiple conditional judgments, rational use of different forms of ifstatements can make the logic of the program clearer and more intelligent.

2.2 `switch`Statement

In the C language, switcha statement is a control statement used for multiple conditional selection. It allows caseto choose to execute different blocks of code among multiple branches based on the value of an expression. switchStatements can make programs more concise and easier to understand, especially when dealing with multiple fixed values.

2.2.1 Basic syntax

switchThe basic syntax of the statement is as follows:

switch (表达式) {
    
    
    case 值1:
        // 当表达式的值等于值1时，执行这里的代码
        break;
    case 值2:
        // 当表达式的值等于值2时，执行这里的代码
        break;
    // 更多case...
    default:
        // 如果表达式的值不匹配任何case时，执行这里的代码
}

表达式is an evaluable expression whose value will casebe compared with each label.
Each casetag is followed by a value to match and a colon.
If 表达式the value of casematches a label, casethe code block under that label will be executed. After executing a block of code, you can breakstep out of switcha statement using the statement to prevent further execution of other caseblocks. If there are no breakstatements, the program will continue with the next one case.

2.2.2 Examples

Consider the following example, which demonstrates how switchstatements can be used to handle operations corresponding to different operators:

#include <stdio.h>

int main() {
    
    
    char operator;
    double num1, num2;

    printf("Enter an operator (+, -, *, /): ");
    scanf(" %c", &operator);

    printf("Enter two numbers: ");
    scanf("%lf %lf", &num1, &num2);

    switch (operator) {
    
    
        case '+':
            printf("%.2lf + %.2lf = %.2lf\n", num1, num2, num1 + num2);
            break;
        case '-':
            printf("%.2lf - %.2lf = %.2lf\n", num1, num2, num1 - num2);
            break;
        case '*':
            printf("%.2lf * %.2lf = %.2lf\n", num1, num2, num1 * num2);
            break;
        case '/':
            if (num2 != 0) {
    
    
                printf("%.2lf / %.2lf = %.2lf\n", num1, num2, num1 / num2);
            } else {
    
    
                printf("Error: Division by zero.\n");
            }
            break;
        default:
            printf("Invalid operator.\n");
    }

    return 0;
}

In this example, the user is first asked to enter an operator, followed by two numbers. Programs use switchstatements to perform different calculations based on operator selection, and to output the results. Depending on the operator, the program will choose to execute the corresponding casebranch.

switchStatements are useful when you need to decide which piece of code to execute based on multiple fixed options. Using switchstatements can make the code structure more tidy and easier to maintain. Note, however, that statements caseare used in each branch breakto avoid unnecessary penetration .

2.2.3 Penetration

In the statement of C language switch, if caseno statement is used in a branch break, the program will "penetrate" to the next casebranch to continue execution without skipping the subsequent ones case. This phenomenon is called "penetration" or "fall-through".

Consider the following example:

#include <stdio.h>

int main() {
    
    
    int choice;

    printf("Enter a number between 1 and 3: ");
    scanf("%d", &choice);

    switch (choice) {
    
    
        case 1:
            printf("You chose 1.\n");
        case 2:
            printf("You chose 2.\n");
        case 3:
            printf("You chose 3.\n");
        default:
            printf("Invalid choice.\n");
    }

    return 0;
}

In this example, if the number entered by the user is 1, the program will output:

You chose 1.
You chose 2.
You chose 3.
Invalid choice.

This is because case 1no statement is used in the code block of break, so the program continues with the next case, and all subsequent code blocks, until switchthe statement ends or is encountered break. This leads to the phenomenon of penetration.

To avoid accidental penetration , it is common caseto use breaka statement at the end of each branch's code block. breakStatements are necessary if you want each branch to execute independent logic without penetrating into other branches . Can be optionally omitted if intentional penetration is desired break, but in this case special care is required to ensure the expected behavior of the code.

Three, loop statement

Mastering loop statements is a crucial step in the journey of learning programming. As a widely used programming language, C language provides a variety of loop statements for handling repetitive tasks. This chapter will help you understand step by step for, , whileand do-whilethree cycles, and provide detailed guidance for your learning path.

3.1 `for`cycle

forLoops are often used to repeatedly execute code a known number of times. It consists of three key parts:

Initialization: A statement executed before the loop begins, usually to initialize a counter.
Condition: A condition that is checked before each loop iteration, and if the condition is true, the loop will continue executing.
UPDATE: A statement executed after each loop iteration, typically used to increment or decrement a counter.

Example: Let us foroutput the first 10 natural numbers using a loop.

#include <stdio.h>

int main() {
    
    
    for (int i = 1; i <= 10; i++) {
    
    
        printf("%d ", i);
    }
    return 0;
}

3.1.1 `break`and`continue`

When the and statements forare used in a loop in C language , they are used to control the break and skip of the loop respectively.breakcontinue

breakstatement

breakstatement is used inside the loop to interrupt the execution of the loop, whether or not the loop condition is met. Once breakthe statement executes, the loop will terminate immediately and program execution will continue with the code following the loop.

Example: Use breakstatement forto find the first number that satisfies a condition in a loop and terminate the loop.

#include <stdio.h>

int main() {
    
    
    for (int i = 1; i <= 10; i++) {
    
    
        if (i == 5) {
    
    
            printf("找到满足条件的数字：%d\n", i);
            break;  // 循环中断
        }
    }
    return 0;
}

continuestatement

continuestatement is used to skip the remainder of the current loop iteration and continue to the next iteration. It will not execute continuethe code following the statement in the current iteration, but will go directly to the next loop iteration.

Example: Use continuea statement to skip the output of some specific numbers.

#include <stdio.h>

int main() {
    
    
    for (int i = 1; i <= 10; i++) {
    
    
        if (i % 2 == 0) {
    
    
            continue;  // 跳过偶数
        }
        printf("%d ", i);
    }
    return 0;
}

When using these statements, be aware of their scope of influence. breakbreaks the loop immediately and exits the loop body, but continuesimply skips the remainder of the current iteration and continues with the next iteration. Using these statements can control the behavior of the loop more flexibly, making the code logic clearer and more readable.

In short, breakis used to break out of the loop entirely, whereas continueit is used to skip the current iteration. These two keywords can help you better handle the logic in the loop in different situations.

3.1.2 Loop Control Variables

1. Do not modify the loop variable in forthe loop body to prevent the loop from getting out of control:

forLoop control variables are defined in the initialization part of the loop and updated in the update part after each iteration. Modifying the loop control variable inside the loop body may cause the loop condition to no longer be satisfied, causing problems with the loop behavior, or even an infinite loop.

Example: Example of incorrectly modifying loop control variables.

#include <stdio.h>

int main() {
    
    
    for (int i = 1; i <= 5; i++) {
    
    
        printf("%d\n", i);
        i--;  // 错误：在循环体内修改循环控制变量
    
    return 0;
}

2. It is suggested that forthe value of the loop control variable of the statement should be written in the "before closing and then opening interval" method:

Using the "close before open interval" writing method can avoid the problem of the boundary value of the loop condition, and also make the behavior of the loop clearer and easier to understand.

Example: A loop using the notation "close before and open after" for.

#include <stdio.h>

int main() {
    
    
    // 从1到10（包括1，不包括10）
    for (int i = 1; i < 10; i++) {
    
    
        printf("%d\n", i);
    }
    return 0;
}

In this way of writing, ithe value of the loop variable starts from 1, and <the number is used in the condition part to ensure that the loop does not execute to 10.

3. Reasonably choose the name of the loop control variable:

Loop control variables should be named descriptively to make code more readable. Often, using concise and meaningful variable names makes the code more clearly communicate the intent of the loop.

Example: Loop with descriptive variable names for.

#include <stdio.h>

int main() {
    
    
    int num_of_students = 10;
    for (int student_id = 1; student_id <= num_of_students; student_id++) {
    
    
        printf("处理学生 %d\n", student_id);
    }
    return 0;
}

In this example, the loop control variable student_idclearly represents the student number being processed.

3.1.3 Loop variants

The loop in C language forcan have many variants, which can be adapted to different situations according to different needs and scenarios.

Here are some examples of common forloop variants:

1. Reverse cycle:

Typically, forloops are incremented from an initial value to an end value, but you can also use this for a reverse loop. This can be achieved by decrementing the loop control variable.

Example: Use fora loop to output numbers from 10 to 1 in reverse order.

#include <stdio.h>

int main() {
    
    
    for (int i = 10; i >= 1; i--) {
    
    
        printf("%d\n", i);
    }
    return 0;
}

2. Infinite loop:

Sometimes it is necessary to create an infinite loop, which can be achieved by using or non-zero value in the loop condition part true.

Example: Using forloop to create an infinite loop, which needs to be broken manually.

#include <stdio.h>

int main() {
    
    
    for (;;) {
    
    
        printf("这是一个无限循环\n");
        // 添加适当的中断条件，如按下Ctrl+C
    }
    return 0;
}

3. Multi-variable loop:

forA loop can initialize multiple loop control variables simultaneously in the initialization section and update them in the update section.

#include <stdio.h>

int main() {
    
    
    for (int i = 1, j = 1; i <= 9; ) {
    
    
        printf("%d * %d = %d\n", i, j, i * j);
        j++;
        if (j > i) {
    
    
            i++;
            j = 1;
        }
    }
    return 0;
}

These are forsome common variants of loops, but there are many more, which can be adjusted appropriately according to actual needs. forLoops are very flexible and can be used in a variety of different looping scenarios. Depending on the situation, choosing the appropriate loop variant can make your code more concise, efficient, and readable.

3.2 `while`cycle

In C, whilea loop is a powerful looping construct that allows you to repeatedly execute a section of code while a condition is true. Compared with forloops, whileloops are more flexible and are suitable for scenarios where the number of loops needs to be dynamically controlled according to conditions. Let's dive into whilethe syntax of loops, how they work, and some common uses.

3.2.1 Grammar

while (条件) {
    
    
    // 循环体代码
}

3.2.2 Working principle

whileThe loop checks to see if the condition is true before each loop starts. The body of the loop will be executed as long as the condition is true. When the loop body is executed, the condition is checked again, and then it is decided whether to continue the next loop. If the condition is false, the loop will terminate and the program will continue executing the code following the loop.

Example: Use whilea loop to calculate the square of a user-entered number.

#include <stdio.h>

int main() {
    
    
    int number, square;

    printf("请输入一个整数：");
    scanf("%d", &number);

    while (number != 0) {
    
    
        square = number * number;
        printf("数字 %d 的平方是 %d\n", number, square);

        printf("请输入一个整数：");
        scanf("%d", &number);
    }

    printf("循环结束，感谢使用！\n");
    return 0;
}

3.2.3 Common usage

Handling user input: Use whilea loop to repeatedly get user input until a certain condition is met.

Processing file content: You can use whilea loop to read the file content line by line until the end of the file.

Dynamic calculation: When the number of loops cannot be determined in advance, whileloops can be used to dynamically calculate the number of loops based on conditions.

Infinite Loop: Can be used while (1)to create an infinite loop and then break the loop under appropriate conditions.

Game loop: The game loop commonly used in game development is based on whileloops.

whileThe flexibility of loops makes them useful in many programming scenarios. However, as with other loops, be careful not to create an infinite loop, and make sure the loop condition can be false at some point, thereby terminating the loop.

3.2.4 `break`Statements and`continue`

In whilea loop, you can also use breakand continuestatements to control the flow of the loop. These keywords whilework similarly in loops as they do in other loop types.

break statement:

breakstatement is used whileinside a loop to immediately terminate the execution of the loop, whether or not the loop condition is true. When breakthe statement is executed, the loop ends immediately, and program execution continues with the code following the loop.

Example: Use whilea loop to find the first number that satisfies a condition and terminate the loop.

#include <stdio.h>

int main() {
      
      
    int number = 1;

    while (number <= 10) {
      
      
        if (number == 5) {
      
      
            printf("找到满足条件的数字：%d\n", number);
            break;  // 循环中断
        }
        number++;
    }

    return 0;
}

continue statement:

continuestatement is used to skip the remainder of the current loop iteration and go directly to the next loop iteration. It terminates the loop body portion of the current iteration, then checks the loop condition to decide whether to continue to the next iteration.

Example: Use whilea loop to output odd numbers.

#include <stdio.h>

int main() {
      
      
    int i = 1;

    while (i <= 10) {
      
      
        if (i % 2 == 0) {
      
      
            i++;
            continue;  // 跳过偶数
        }
        printf("%d\n", i);
        i++;
    }

    return 0;
}

breakAND continuestatements whilework the same in loops as they do in other loops. They can realize conditional jumping and skipping requirements inside the loop, helping you to control the execution flow of the loop more precisely. But make sure that when you use them, you don't cause an infinite loop or skip a significant part of the loop.

3.3 `do-while`cycle

do-whileA loop is a loop structure in the C language. It is whilesomewhat similar to a loop, but there is an important difference: do-whilethe loop first executes the loop body once, and then checks whether the loop condition is satisfied after each iteration. Let's dive into do-whilethe syntax of loops, how they work, and some common use cases.

3.3.1 Grammar

do {
    
    
    // 循环体代码
} while (条件);

3.3.2 Working principle

do-whileA loop first executes the code in the loop body once, and then checks whether the loop condition is true. The loop continues to iterate as long as the condition is true, continues executing the loop body, and then checks the loop condition again. If the condition is false, the loop will terminate and the program will continue executing the code after the loop.

Example: Use do-whilea loop to get user input until the input is valid.

#include <stdio.h>

int main() {
    
    
    int number;

    do {
    
    
        printf("请输入一个正整数：");
        scanf("%d", &number);
    } while (number <= 0);

    printf("您输入的是：%d\n", number);
    return 0;
}

3.3.3 Common usage

User Input Validation: Use do-whilea loop to ensure that the user enters at least once and validate the input on each iteration.

Menu selection: In scenarios such as menu selection, do-whilea loop can be used to continuously display options and wait for the user to select until the user chooses to exit.

Handle user feedback: You can use do-whilea loop to get user feedback, and then decide whether to continue execution based on the feedback.

Simulate game turns: Turn-based operations in games can be do-whileimplemented using loops.

do-whileThe loop ensures that the loop body will be executed at least once, which is suitable for situations where some operations need to be performed before the loop. Note that the loop condition must be at the end of the loop body, this ensures that the loop body is executed at least once.

3.3.4 `break`Statements and`continue`

break statement

breakstatement is used do-whileinside a loop to immediately terminate the execution of the loop, whether or not the loop condition is true. When breakthe statement is executed, the loop ends immediately, and program execution continues with the code following the loop.

Example: Use do-whilea loop to find the first number that satisfies a condition and terminate the loop.

#include <stdio.h>

int main() {
      
      
    int number = 1;

    do {
      
      
        if (number == 5) {
      
      
            printf("找到满足条件的数字：%d\n", number);
            break;  // 循环中断
        }
        number++;
    } while (number <= 10);

    return 0;
}

continue statement

continuestatement is used to skip the remainder of the current loop iteration and go directly to the next loop iteration. It terminates the loop body portion of the current iteration and starts a new iteration.

Example: Use do-whilea loop to output odd numbers.

#include <stdio.h>

int main() {
      
      
    int i = 1;

    do {
      
      
        if (i % 2 == 0) {
      
      
            i++;
            continue;  // 跳过偶数
        }
        printf("%d\n", i);
        i++;
    } while (i <= 10);

    return 0;
}

breakAND continuestatements do-whilework the same in loops as they do in other loops. They can all be used to implement conditional jumps and skips inside the loop, helping you control the execution flow of the loop more flexibly. Make sure that when you use them, you don't cause an infinite loop or skip a significant part of the loop.

3.4 `goto`Statements

gotoA statement is a type of jump statement in the C language that allows a direct jump to another label (or identifier) location in the program. However, it is worth noting that using gotostatements can lead to code that becomes difficult to understand and maintain, so they should be used with caution in programming.

3.4.1 Basic syntax

In the C language, gotothe basic syntax of a statement is as follows:

goto label;
// ...
label:
// 代码段

The above code will gotojump the control flow of the program from the statement to labelthe location of the label

3.4.2 Examples

When it comes to gotousage examples of statements, we can consider a simple error handling scenario. Let's say we're writing a function that reads data from a file and needs error handling if the read fails.

Here is a gotosimple example of a usage statement:

#include <stdio.h>

int main() {
    
    
    FILE *file = fopen("data.txt", "r");
    if (file == NULL) {
    
    
        printf("Failed to open the file.\n");
        goto error;
    }

    // 读取文件中的数据
    // ...

    fclose(file);
    return 0;

error:
    // 错误处理逻辑
    printf("An error occurred.\n");
    return 1;
}

In the above example, if the file cannot be opened, the program will jump to the label errorfor error handling. In this case, gotostatements can help us avoid rewriting error handling logic when an error occurs.

3.4.3 Advantages

Although gotothe statement is viewed with skepticism in modern programming practice, it can still help in some specific situations:

Error Handling: When handling errors, gotostatements let you jump to a shared block of error-handling code to avoid rewriting the same error-handling logic at every error checkpoint.

Complex jump logic: Sometimes, some algorithms or logic may require complex jump paths, and gotothese logics can be expressed more clearly.

3.4.4 Disadvantages

However, gotothe use of statements also poses some serious problems:

Poor readability: Using gotostatements can cause the code to become difficult to understand. Since it allows jumping between different locations, the flow of program execution can become confusing.

Difficult to maintain:goto Using statements can lead to difficult-to-maintain code when the codebase grows large and multiple people collaborate . Using statements in different places gotocan make code difficult to follow and debug.

Potential for dangling pointers: If the statement is used carelessly goto, it can lead to dangling pointers, which point to uninitialized or freed memory regions.

3.4.5 Alternatives

Although gotostatements may be useful in some situations, in modern programming, structured control flow statements such as , , , ifetc. whileare forgenerally preferred to implement logic and control flow.

Summarize

When it comes to the use of control flow statements in C, we've explored several key ones in depth: forloops, switchstatements, whileloops, do-whileloops, and gotostatements. Each statement has its unique advantages and applicable situations, but in actual programming, we need to choose the most suitable control flow structure according to the specific situation.

forLoop is preferred when the number of loops is known. It has a clear structure and is useful when the number of loops is specified.

switchStatements are useful for selecting among multiple options. It can map different cases to different code blocks, making the code more readable.

whileLoops are used to repeatedly execute code while a condition is true. It is suitable for situations where you need to loop until a certain condition is not met.

do-whileA loop whileis similar to a loop, but it guarantees that the loop body is executed at least once. This is useful for scenarios where the body of the loop needs to be executed before the condition check.

gotoA statement is an unconditional jump facility, and while it may be useful in some situations, it should generally be avoided in modern programming to ensure code readability and maintainability.

Proper selection of appropriate control flow structures is a critical step in writing high-quality code. Whether the number of iterations is known or multi-way branch selection is required, we should choose the appropriate structure according to the logic and requirements of the code. At the same time, structured control flow statements help to improve code readability and maintainability, thereby promoting better programming practices.

"Introduction to C Language" branch and loop statement

Article directory

introduction

1. What is a statement?

1.1 Expression statement

1.2 Assignment statement

1.3 Function call statement

1.4 Compound Statements

1.5 Empty statement

1.6 Control Statements

Two, branch statement

2.1 ifStatement

2.1.1 Basic syntax

2.1.2 Using elseStatements

2.1.3 Nested if statements

2.1.4 Multi-layer if-elsestatements

2.2 switchStatement

2.2.1 Basic syntax

2.2.2 Examples

2.2.3 Penetration

Three, loop statement

3.1 forcycle

3.1.1 breakandcontinue

3.1.2 Loop Control Variables

3.1.3 Loop variants

3.2 whilecycle

3.2.1 Grammar

3.2.2 Working principle

3.2.3 Common usage

3.2.4 breakStatements andcontinue

3.3 do-whilecycle

3.3.1 Grammar

3.3.2 Working principle

3.3.3 Common usage

3.3.4 breakStatements andcontinue

3.4 gotoStatements

3.4.1 Basic syntax

3.4.2 Examples

3.4.3 Advantages

3.4.4 Disadvantages

3.4.5 Alternatives

Summarize

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2.1 `if`Statement

2.1.2 Using `else`Statements

2.1.4 Multi-layer `if-else`statements

2.2 `switch`Statement

3.1 `for`cycle

3.1.1 `break`and`continue`

3.2 `while`cycle

3.2.4 `break`Statements and`continue`

3.3 `do-while`cycle

3.3.4 `break`Statements and`continue`

3.4 `goto`Statements