我正在尝试在我的C++应用程序上使用线程.

我的代码是:

#include <iostream>
#include <thread>

class C
{
public:

    void * code( void * param )
    {
        std::cout << "Code thread executing " << std::endl;
        return NULL;
    }
};

int main()
{
    C c;
    std::thread t ( &C::code, &c );
    t.join();
}

编译时,我得到了这些错误:

In file included from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/bits/move.h:57:0,
                 from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/bits/stl_pair.h:61,
                 from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/bits/stl_algobase.h:65,
                 from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/bits/char_traits.h:41,
                 from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/ios:41,
                 from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/ostream:40,
                 from /opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/iostream:40,
                 from C.cpp:1:
/opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/type_traits: In instantiation of 'struct std::_Result_of_impl<false, false, std::_Mem_fn<void* (C::*)(void*)const>, C*>':
/opt/centos/devtoolset-1.0/root/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../include/c++/4.7.0/type_traits:1857:12:   required from 'class std::result_of<std::_Mem_fn<void* (C::*)(void*)const>(C*)>'

还有更多...... …

我想了解为什么动态分配多次调用的数据使用的内存比在代码上直接指定的内存或通过单次调用分配的那样多malloc.

例子

例如,我在C中制作了以下两个代码:

test1.c:int x分配有malloc

int main (void)
{
    int *x;
    int i, n=1048576; //n=1024*1024;

    printf("size = %lu\n", n* sizeof(int));

    for(i=0; i<n; i++)
    {
        x = malloc(sizeof(int));
        *x=i;
    }
    printf("Look at top and then press something to finish.");fflush(stdout);
    getc(stdin);
    return 0;
}

我没有在这里免费使用它来保持简单.当程序等待交互时,我查看另一个终端中的top函数,它显示了这个:

PID  USER   PR  NI  VIRT   RES    SHR  S  %CPU %MEM  TIME+   COMMAND                                    
1384 root   20  0   41300  34076  1300 S  0.0  3.3   0:00.47 test1

test2.c:int x未动态分配

int main (void)
{ …