[First familiar with C language] Variables, variable definition, initialization and assignment

1. Variable

The variable is the amount of change.
In C language, constants are used to represent unchanging values, and variables are used to represent changing values.
eg: output 26 letters

#include <stdio.h>
int main()
{
    
    
	char c = 'A';//定义一个为char类型的变量c,并对其进行初始化
	for (; c <='Z'; c++)
	{
    
    
		printf("%c", c);
	}
	printf("\n");
	return 0;
}

2. Definition of variables

int temp;
int age = 21;
float weight = 51.2f; 
char ch = 'V';

2.1 Variable definition format

int a = 10;
type variable name assignment operator content

2.2 Defining the nature of variables

Open up a space corresponding to the size of the variable in the computer memory.

2.3 Initialization and assignment of variables

Initialization: Assign values ​​to variables when they are defined.
eg: int age = 21;

Assignment: Assign a new value to an existing variable.
eg: age=22;

(1) float weight = 45.5f; It is recommended to bring f when representing a floating-point number of float type, and do not use double type.
(2) int temp; If the variable is not initialized when it is defined, the system will assign a random value to it.