C++函數庫調用實現計時器

#include <iostream>
#include<ctime>

using namespace std;

int main()
{
    cout << "Hello world!" << endl;
    cout<<"Enter the delay time,in seconds: ";
    float secs;
    cin>>secs;
    clock_t delay=secs*CLOCKS_PER_SEC;
    cout<<"starting\a\n";
    clock_t start=clock();
    while(clock()-start<delay)
        ;
    cout<<"done\a\n";
    return 0;
}