What is the difference between a++ and ++a in C language

The difference between a and a in C language is: the operation process of the two is different. a means to use the value of a first, and then add 1 to a; a means to add 1 to a first, Then use the value of a again. Both a and a are equivalent to [a = a 1].

Auto-increment operator:

is an auto-increment operator: such as a, a is equivalent to a = a 1;

So what is the difference between a and a?

Although the equivalent results of a and a are the same, the operation processes are different. a means to use the value of a first, and then add 1 to a; a means to add 1 to a first, and then use the value of a.

Let’s take a look at an example:

    #include <stdio.h>  
    int main()  
    {  
        //int m = 10, n1, n2;  
        //n1 = m++;先将m的值赋给n1，然后m再做自增运算，所以此时，n1=10,m=11;  
        //n2 = ++m ;先将m做自增运算，然后在将运算后的m值赋给n2，所以此时，n2=11，m=11；  
      
        int a = 10,b =10, c, d;  
        c = (a++) + (++a);  
        //由上例n1=m++,n2=++m,m++=11可得出c=10+12;分析：前面括号所得值为10，而前面括号中的a经过自增运算后a的值为11，然后赋值给后面括号中的a，后面括号中的a经过自增运算后a的值为12，后面括号最后赋值为12；  
        d = (++b) + (b++);  
        //由上例n1=m++,n2=++m,++m=11可得出d=11+11;分析：前面括号所得值为11，而前面括号中的a经过自增运算后b的值为11，然后赋值给后面括号中的b，后面括号中的b先将值赋给后面括号，所以后面括号的值为11；  
        printf("c=%d\nd=%d\n",c,d);  
        return 0;  
    }

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