C语言四舍五入函数lrintf（）用法

函数定义在math.h

'''

inline long __cdecl lrintf (float x) 

{

long retval;

__asm fld x

__asm fistp retval

return retval;

}

'''

测试程序：

'''

#include

#include

#include

using namespace std;

int main(int argc, char * const argv[])

{

float a[5] = {-1.8,-1.2,-0.5,0,0.8};

int b[5] = { 0 };

int c[5] = { 0 };

int d[5] = { 0 };

cout << "a[i]  " << "a[i]取整  " << "a[i]-0.5取整  " << "a[i]+0.5取整" << endl;

for (int i = 0;i<5;i++)

{

a[i] = i;

b[i] = lrintf(a[i]);

c[i] = lrintf(a[i] - 0.5);

d[i] = lrintf(a[i] + 0.5);

//cout << a[i]  << "  " << b[i] << "  " << c[i] << "  " << d[i] << "  " << endl;

printf("%f\t%d\t%d\t%d\n", a[i], b[i], c[i], d[i]);

}

}

'''