Basics of C++ programming [1]
1. The development steps of a program
1. Edit program
Use a text editor to write and edit the program, and save the written program ( source file ) to the disk as the input of the editor
2. Compile the program
Translate source files into machine language by a compiler
3. Link program
The linker assembles system functions and functions in the source program into an executable file
4. Execute the program
Load the program into memory through the loader
5. Test
Program testing by building test cases
2. Basic code interpretation
1. Preprocessing directive (#include)
The preprocessor checks the preprocessing commands, then the compiler performs the operations required in the commands, then removes the preprocessing commands, and finally compiles
2. Block comments (/* */)
Block comments are used to display comments to users or code reviewers, and are completely ignored by the compiler
3. Line comments (//)
The entire line is ignored by the compiler
4.using namespace std
When an object has no last name, insert std:: in front of it, making its name complete
5.int main()
Every C++ program starts with the main function
6.{}
Curly braces must be paired, and every function definition must be enclosed within them
7.std::cin、std::cout、std::endl
std is the standard library, cout and endl are objects
. To avoid direction confusion, it can be simply understood as >> is input, data moves to the right, << is output, and data moves to the left. The
object of cin is the variable name, and the object of cout is the value
8.return 0
When the C++ runner waits and returns 0, the program runs successfully and ends the program
2. Variables, values, constants
1. Variables
Before using a variable, you must first define the variable, tell the compiler to use a memory location with a given name and a given type, and if the variable is declared without a given value, no value is stored
2. value
The content of the variable is called the "value"
3. Constants
The value of a constant cannot be changed. When declaring its memory location, use the const modifier to limit its name (it is not recommended to use literals)
Three, the components of a C++ program
1. Identifier
A C++ program without comments is a sequence of tokens. Tags contain identifiers, literals, or symbols
1. Identifier
Identifiers must start with a letter or underscore and can contain an unlimited number of numbers, letters or underscores
Identifiers can be attributed to keywords, predefined identifiers and user-defined identifiers
1. Keyword
Keyword cannot be redefined, keyword
2. Predefined identifiers
Do not change the predefined
3. User-defined identifier
If the identifier we define is descriptive, the name can describe the content of the entity
2. Literal
Literals are constant values of different types, including integers, strings, etc.
3. Symbol
C++ uses non-alphabetic symbols as operators and punctuation marks, refer to the link
1. Arithmetic operators
2. Relational operators
3. Logical operators
4. Bitwise operators
5. Assignment operator
6. Miscellaneous operators
7. Operation priority
4. Data type
The data types are classified as follows and
the value ranges are as follows
1. Integer type
2. Character type
Character literals are always enclosed in single quotes
3. Boolean type
Boolean data types have a size of one byte
4. Floating point type
5. void type
6. String class
In C language, the string ends with a null character, the actual string length +1 (+'\0'), in C++ the string class is used, there is no null character
1. Why is the format of the C++ project .h, .cpp
The header file .h is
Source File