01. Program and program structure
Program concept: a program written by a computer in order to realize a certain function
Sequence structure: execute in the order of the program
Select the structure: judge according to the given conditions, and determine the next step of execution by the result of the judgment
Cyclic structure: within the scope of the conditions, repeated execution
The essence of the condition is ultimately a Boolean value
02: if selection structure
Concept: a grammatical structure that is processed after judgment based on conditions
Usage: When the first condition is not established, the second condition is executed, and the else is not satisfied.
Example:
if (条件一)
{
条件一成立之后执行的程序
}
else if (条件二)
{
条件一不成立，条件二成立之后执行的程序
}
else
{
两个条件都不成立时执行的程序
}
03: switch structure
Concept: used to deal with fixed value branches
Usage:
int a = int.Parse(Console.ReadLine()); / Receive keyboard input and convert to integer
switch(a)
{ case 1: the program executed by /a=1 Console.WriteLine("a=1"); /print output break; case 2: the program executed by /a=2 Console.WriteLine("a=2" ); /Print output break; default: / The program that does not satisfy the execution Console.WriteLine("a is not equal to 1 and 2"); /Print output
Attributes:
Break: The meaning of breaking will make the code jump out of the entire loop body. C# must add this attribute after each.
Default: When it is not satisfied, execute the program
04: While and for loop structure
concept: within the scope of the establishment of conditions, repeated carried out;
while(): basic loop structure
while (condition)
{ program executed in a loop after the condition is established } 1 2 3 4 do{}while(): execute at least once, and then judge the condition do { program that loops at least once } while (condition ) for(): Fill in the brackets with the initial value, loop condition, and condition change for (condition variable: initial value; loop condition; change in condition variable) { program to be executed in a loop after the condition is established } Properties:
continue skip this round of loop, the next round will continue to
break out of the entire loop body, the code behind the loop body will be executed