如何在运行时按名称访问结构字段? [英] How can I access structure fields by name at run time?

问题描述

C 常见问题解答以某种方式解释它，这里是链接.>

但是我看不懂，谁能帮我解释一下?或者给我另一种方式?

非常感谢！

解决方案

我认为这个例子已经说明了答案:

结构测试{国际b;一个;};int main(){测试 t;测试* structp = &t;//在结构中找到'a'的字节偏移量int offsetf = offsetof(test, a);//使用指针算法设置'a'的值*(int *)((char *)structp + offsetf) = 5;返回0；}

The C faqs explain it in a way, here is the link.

But I can't understand it, Somebody can explain it for me? Or give me another way?

Thanks so much!

解决方案

I think this example makes the answer clear:

struct test
{
    int b;
    int a;
};

int main() 
{
    test t;
    test* structp = &t;

    //Find the byte offset of 'a' within the structure
    int offsetf = offsetof(test, a);

    //Set the value of 'a' using pointer arithmetic
    *(int *)((char *)structp + offsetf) = 5;

    return 0;

}

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