当我尝试实现多线程时如何删除这些烦人的警告 [英] how to remove these annoying warnings when I try to implement multithread

问题描述

这是代码.

Hi, here is the code.

...
int x;  // assume this is the parameter of the function thread
pthread_t t1;
pthread_create(t1,NULL,thread,(void *)x);
...

void *thread(void *arg)
{
int x=(int)arg;
}

由于我需要将值传递给线程，
所以我该如何摆脱以下警告:
警告:从不同大小的整数强制转换为指针...

Since I need to pass value to the thread,
so how can I get rid of the following kind of warnings:
warning: cast to pointer from integer of different size .....

Thanks a bunch!

推荐答案

好吧，如果要构建64位Linux，则指针的大小(void *)大于指针的大小. int，所以您不能打字.您可以使用"long"代替"int".

关于"int"是在32位编译器上是32位还是在64位编译器上是64位，存在一些争论.它似乎取决于编译器.您应该检查一下它上的内容.

通常，

sizeof(int)= 32
sizeof(long)= 64
sizeof(void *)= 64(在64位编译器上，否则为32)

Well, if you''re building 64-bit Linux, the size of a pointer (void *) is bigger than the size of an int so you can''t typecast it. You could use "long" instead of "int".

There is some debate on if "int" is 32-bits on 32 bit compilers and 64-bits on 64 bit compilers. It seems to be compiler dependent. You should check what it is on yours.

Typically,

sizeof(int) = 32
sizeof(long) = 64
sizeof(void *) = 64 (on 64-bit compilers, otherwise 32)

您确定您不对我们的代码样本感到满意吗?我问是因为任何不错的C ++编译器都应该产生编译错误，而不是警告.您的函数应返回void *指针.它不能编译，否则就不能编译.

—SA

Are you sure you are not fulling us with this code sample? I''m asking because any decent C++ compiler should produce a compilation error, not a warning here. Your function should return void * pointer. It cannot compile is it does not.

—SA

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