极品_Bool在C99？ [英] Need for _Bool in C99?

问题描述

我正在读一本关于C.
它说，C99增加了一个数据类型_Bool。
它基本上是一个int，但只存储0或1。
现在，我不明白为什么有必要这样的数据类型。
我们已经有了布尔含蓄地转化为int，反之亦然。
因此，有人可以告诉我的情况是这样的数据类型将是有益的。

PS：C ++似乎不支持这种数据类型所看到这里

 的#include＆LT;＆iostream的GT;
使用命名空间std;诠释主（）{
    //你的code到这里
    _Bool B = FALSE;
    如果（二== 0）
        输出（假）;
    其他
        的printf（TRUE）;
    返回0;
}
 

解决方案

  

它说，C99加入了可变_Bool

没有，C99增加了一个内置的名为type _Bool ，它可以有两种 0 或值 1 。头，＆LT; stdbool.h＆GT; 定义宏在布尔扩展到 _Bool ，假到 0 和真正到 1 。

C ++，在另一方面，有一个内置的名为type 布尔，它可以有值真正和假。出于兼容性考虑，C ++ 11指定 stdbool.h 应该是present，而空。 （有些C编译器提供的C ++的布尔作为扩展pre-C99）。

与C99新增的意图是提供相同的设施，C ++，但是这并不能否定旧C89 code（一种方式，其中纯布尔是可作为名称）。在我看来，宏观的解决方案，他们想出了不太理想，而事实上它仍然是相当罕见请参阅C code，它使用布尔类型，而它们普遍在C ++中。

I am reading a book on C. It says that C99 added a data type _Bool. It is basically an int but stores only 0 or 1. Now I do not understand why there is a need of such a data type. We already have bool which implicitly translates to int and vice versa. So can somebody please tell me a situation where such a data type would be useful.

PS: C++ does not seem to support such a data type as seen here.

#include <iostream>
using namespace std;

int main() {
    // your code goes here
    _Bool b = false;
    if(b == 0)
        printf("FALSE");
    else
        printf("TRUE");
    return 0;
}

解决方案

It says that C99 added a variable _Bool

No, C99 added a built-in type called _Bool, which can have values of either 0 or 1. The header, <stdbool.h> defines macros in which bool expands to _Bool, false to 0, and true to 1.

C++, on the other hand, has a built in type called bool, which can have values of true and false. For compatibility, C++11 specifies that stdbool.h should be present, but empty. (Some C compilers provided C++'s bool as an extension pre-C99.)

The intention with the C99 additions was to provide the same facilities as C++, but in a way that didn't invalidate old C89 code (where plain bool was available as a name). In my opinion the macro solution they came up with is less than ideal, and indeed it's still quite rare to see C code which uses the boolean types, whereas they are pervasive in C++.

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