running.c

C Primer Plus(第五版)中文版,不用多说了

// running.c -- A useful program for runners 
#include <stdio.h>
const int S_PER_M = 60;         // seconds in a minute  
const int S_PER_H = 3600;       // seconds in an hour   
const double M_PER_K = 0.62137; // miles in a kilometer 
int main(void)
{
    double distk, distm;  // distance run in km and in miles 
    double rate;          // average speed in mph
    int min, sec;         // minutes and seconds of running time
    int time;             // running time in seconds only
    double mtime;         // time in seconds for one mile
    int mmin, msec;       // minutes and seconds for one mile

    printf("This program converts your time for a metric race\n");
    printf("to a time for running a mile and to your average\n");
    printf("speed in miles per hour.\n");
    printf("Please enter, in kilometers, the distance run.\n");
    scanf("%lf", &distk);  // %lf for type double
    printf("Next enter the time in minutes and seconds.\n");
    printf("Begin by entering the minutes.\n");
    scanf("%d", &min);
    printf("Now enter the seconds.\n");
    scanf("%d", &sec);
// converts time to pure seconds 
    time = S_PER_M * min + sec;
// converts kilometers to miles 
    distm = M_PER_K * distk;
// miles per sec x sec per hour = mph 
    rate = distm / time * S_PER_H;
// time/distance = time per mile       
    mtime = (double) time / distm;
    mmin = (int) mtime / S_PER_M; // find whole minutes       
    msec = (int) mtime % S_PER_M; // find remaining seconds   
    printf("You ran %1.2f km (%1.2f miles) in %d min, %d sec.\n",
         distk, distm, min, sec);
    printf("That pace corresponds to running a mile in %d min, ",
         mmin);
    printf("%d sec.\nYour average speed was %1.2f mph.\n",msec,
         rate);
  
    return 0;
}