程序未显示显示处理和计时的窗口

Question

几周前我运行了我的项目，它向我显示了显示时间和处理速度以及它使用的内存的窗口，但现在我在同一个工具上运行相同的代码，但它没有显示那个屏幕。我在 Visual Studio 2010 和 2015 的两个版本上都尝试了相同的代码，但我得到了那个屏幕。

这里是代码

#ifdef __GNUC__
#include <time.h>
float getticks()
{
    struct timespec ts;

    if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0)
        return -1.0f;

    return ts.tv_sec + 1e-9f*ts.tv_nsec;
}
#else
#include <windows.h>
float getticks()
{
    static double freq = -1.0;
    LARGE_INTEGER lint;

    if (freq < 0.0)
    {
        if (!QueryPerformanceFrequency(&lint))
            return -1.0f;

        freq = lint.QuadPart;
    }

    if (!QueryPerformanceCounter(&lint))
        return -1.0f;

    return (float)(lint.QuadPart / freq);
}
#endif

谢谢

Answer 1

不要像那样投射到float。 float 只有 4 个字节，无法处理 QuadPart。而是使用unsigned long long 或long long

LARGE_INTEGER freq;
QueryPerformanceFrequency(&freq);

LARGE_INTEGER t1;
QueryPerformanceCounter(&t1);

//sleep for about 1 second
Sleep(1000);

LARGE_INTEGER t2;
QueryPerformanceCounter(&t2);

long long diff = t2.QuadPart - t1.QuadPart;

//print the result with varying accuracy:
cout << "seconds: "      << 1          * diff / freq.QuadPart << endl;
cout << "milliseconds: " << 1000       * diff / freq.QuadPart << endl; 
cout << "microseconds: " << 1000000    * diff / freq.QuadPart << endl;
cout << "nanoseconds: "  << 1000000000 * diff / freq.QuadPart << endl;

还有GetTickCount64（它是一个精度约为1毫秒的随机计数器）、GetSystemTime和GetSystemTimeAsFileTime ...取决于您要执行的操作。