sizeof操作符返回C和不同的价值观; C ++？ [英] sizeof operator returns different values for c & c++?

问题描述

一个字符数组是全局定义和名称相同的结构，在函数中定义。为什么sizeof操作符返回C和不同的价值观; C ++？

A character array is defined globally and a structure with same name is defined within a function. Why sizeof operator returns different values for c & c++ ?

char S[13];
void fun()
{
    struct S
    {
        int v;
    };
    int v1 = sizeof(S);
}

//返回4 C ++和13用C

// returns 4 in C++ and 13 in C

推荐答案

由于在C ++中，结构您定义被命名为取值，而在C，它的命名的struct （这就是为什么你经常看到使用 typedef结构 C code）。如果你到code更改为以下，你会得到预期的结果：

Because in C++, the struct you defined is named S, while in C, it's named struct S (which is why you often see typedef struct used in C code). If you were to change the code to the following, you would get the expected results:

char S[13];
void fun()
{
    typedef struct tagS
    {
        int v;
    } S;
    int v1 = sizeof(S);
}

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