2010.12.22-time.h包含的庫函數 一些常用的時間函數

這幾個是我一個個試出來的，很好用的。呵呵，希望對你有用！

/*clock計算調用進程使用處理器的時間
函數原型：clock_t clock(void)*/
//實例
//******C語言描述******
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void sleep(clock_t wait);

int main(void)
{
    long i=6000000L;
    clock_t start,finish;
    double duration;
    printf("Delay for three seconds/n");
    sleep((clock_t)3*CLOCKS_PER_SEC);
    printf("Done!/n");
    printf("Time to do %ld empty loops is",i);
    start=clock();
    while(i--);
    finish=clock();
    duration=(double)(finish-start)/CLOCKS_PER_SEC;
    printf("%2.lf seconds/n",duration);
}

void sleep(clock_t wait)
{
    clock_t goal;
    goal=wait+clock();
    while(goal>clock());
}
//******C++語言描述******
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
using namespace std;

void sleep(clock_t wait);

int main(void)
{
    long i=6000000L;
    clock_t start,finish;
    double duration;
    cout<<"Delay for three seconds/n";
    sleep((clock_t)3*CLOCKS_PER_SEC);
    cout<<"Done!/n";
    cout<<"Time to do "<<i <<" empty loops is ";
    start=clock();
    while(i--);
    finish=clock();
    duration=(double)(finish-start)/CLOCKS_PER_SEC;
    cout<<duration<<" seconds/n";
}

void sleep(clock_t wait)
{
    clock_t goal;
    goal=wait+clock();
    while(goal>clock());
}

//******運行結果******
Delay for three seconds
Done!
Time to do 6000000 empty loops is 0.02 seconds
Press any key to continue


//difftime計算t1,t2兩個時間差
//函數原型：double difftime(time_t t1,time_t t2);t1開始時間 ,t2結束時間
//實例：
#include <iostream>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;

int main(void)
{
    time_t start,finish;
    long loop;
    double result,elapsed_time;
    cout<<"Multiplying 2 floating point number 500 million times ..../n";
    time(&start);
    for(loop=0;loop<500000000;loop++)
        result=3.63*5.27;
    time(&finish);
    elapsed_time=difftime(finish,start);
    cout<<"Program takes "<<elapsed_time <<" seconds./n";
    return 0;
}
//******運行結果******
Multiplying 2 floating point number 500 million times ....
Program takes 2 seconds.
Press any key to continue

//asctime把時間日期轉換爲字符串
//函數原型：char *asctime(const struct tm *timeptr);timeptr時間日期結構指針
//實例：
//#include <iostream>
#include <time.h>
#include <stdio.h>
//using namespace std;

struct tm *newtime;
time_t aclock;
int main(void)
{
    time(&aclock);
    newtime=localtime(&aclock);
    printf("current data and time %s",asctime(newtime));
    //return 0;
}
//******運行結果******
current data and time Sun Jul 01 17:23:49 2007
Press any key to continue