#include <stdio.h>
void main()
{
    int a=1,b=2,c=3;
    printf("%3d%3d%3d\n",a,b,c);
    {
        int b=4;
        float c=5.0;
        printf("%3d%3d%5.1f\n",a,b,c);
        a=b;
        {
            int c;
            c=b;
            printf("%3d%3d%3d\n",a,b,c);
        }
        printf("%3d%3d%5.1f\n",a,b,c);
    }
    printf("%3d%3d%3d\n",a,b,c);  //这行里面的a为什么等于4？
}
解释一下注释那行的a，b,c分别为4，2，3

    int a=1,b=2,c=3;
    printf("%3d%3d%3d\n",a,b,c);
    {
        int b=4;
        float c=5.0;
        printf("%3d%3d%5.1f\n",a,b,c);
        a=b;
        {
            int c;
            c=b;
            printf("%3d%3d%3d\n",a,b,c);
        }
        printf("%3d%3d%5.1f\n",a,b,c);
    }
    printf("%3d%3d%3d\n",a,b,c);  //这行里面的a为什么等于4？

那你认为应该是多少呢？

代码块内如果有定义与前面定义的变量同名，那么该代码块内是会屏蔽掉前面定义的那个变量。

这与局部变量的优先级有关

#include "stdio.h"
void main()
{
    int a=1,b=2,c=3;
    printf("%3d%3d%3d\n",a,b,c);
    {
        int b=4;
        float c=5.0;
        printf("%3d%3d%5.1f\n",a,b,c);
        a=b;//a=4,b=a
        {
            int c;
            c=b;//c=4,b=a,c原本为folat,改变成Int，所以c=4而不=0
            printf("%3d%3d%3d\n",a,b,c);//a=4,b=4,c=4
        }
        printf("%3d%3d%5.1f\n",a,b,c);//%5.1f把c定义成float型，所以c=5.0
    }
    printf("%3d%3d%3d\n",a,b,c);  //因为赋值了a=b,所以a=4,因为这行在大挎号外，且定义的是%d的int型，所以c=3
}

这是赋值操作，我懂了

外层变量内层不可见

对，谢谢你！

可以这么说，仅限于同名的变量

[此贴子已经被作者于2016-11-10 11:11编辑过]

已经赋值a=b