a++ 和++a相关的面试题

题目如下

# include <stdio.h>

int main(void)
{
    int a;
    int b;
    int c;
    int d;
    a = 10;
    b = a++;
    c = ++a;
//    d = 10 * ++a;
    d = 10 * a++;
    printf("%d, %d, %d, %d", a, b, c, d);

    return 0;
}

编译后的结果是13, 10, 12, 120

此处有两个重点

1. a++ 和 ++a等价于a = a + 1;
2. b = a++;是先将a的值赋给a再自增类似于b = a; a = a + 1;, c = ++a;是将a先自增再赋给c，类似于a = a + 1; c = a;