C 运算符、表达式和语句

1.一个示例程序

示例程序
//一个对长跑运动员有用的程序
#include<stdio.h>
#define S_PER_H  3600
#define S_PER_M  60
#define S_PER_K   0.62137
int main(void)
{
    double distk,distm;//跑过的路程，公里、英里
    double  rate;//以英里/每小时的单位平均速度
    int min,sec;//跑步用的分钟数和秒钟数
    int time;//用秒表示跑步时间
    double mtime;//跑完以英里所用的时间，以秒计算
    int mmin,msec;//跑完一英里所用的时间，以分钟和秒计算。
    printf("This program converts your time for a metric race
");
    printf("to a time foe running a mile and to your average
");
    printf("speed in miles per hour.
");
    printf("please enter ,in kilometers,the distance run.
");
    scanf("%lf",&distk);//表示读取一个double类型的数值
    printf("Next enter the time in minutes and distance and seconds.
");
    printf("Begin by entering the minutes.
");
    scanf("%d",&min);
    printf("Now enter the seconds.
");
    scanf("%d",&sec);
    //把时间转化为全部用秒表示
    time=S_PER_M*min+sec;
    //把公里转化为英里
    distm=S_PER_K*distk;
    //英里/秒*秒/小时=英里/小时
    rate=distm/time*S_PER_H;
    //时间/距离=跑完每英里用的时间
    mtime=(double)time/distm;
    mmin=(int)mtime/S_PER_M;//求出分钟数
    msec=(int)mtime%S_PER_M;//求出剩余的秒数
    printf("you can %1.2f km(%1.2f miles) in %d min.%d sec.
",
        //如果(%1.2f miles)变成了(%1.2 miles)会怎么样？
        distk,distm,min,sec);
    printf("That pacecorresponds to running a mile in %d min.",min);
    printf("%d sec.
Your average speed was %1.2f mph.
",msec,rate);
    return 0;
}

View Code

关于棋盘麦粒的问题 //关于棋盘麦粒的问题 #include<stdio.h> #define SQUARES 64 #define CROP 1E15 int main(void) { double current,total; int count=1;//棋盘的格子数 printf("square grains added total grains fraction of "); printf(" US total "); total=current=1.0;//开始时是1粒 //total为麦子的总数 //current为当前棋盘格子麦子的数量 printf("%4d %13.2e %12.2e %15.2e ",count,current,total,total/CROP); while(count<SQUARES) { count=count+1; current=2.0*current; //下个方格的粒数加倍 total=total+current;//更新总数 printf("%4d %13.2e %12.2e %15.2e ",count,current,total,total/CROP); } printf("That's all. "); return 0; }

除法运算符/ //除法运算符/ #include<stdio.h> int main(void) { printf("integer division 5/4 is %d ",5/4);//整数除法的小树部分被丢弃 printf("integer division 6/3 is %d ",6/3); printf("integer division 7/4 is %d ",7/4); printf("floating division 7.0/4. is %.2f ",7.0/4.); printf("mixed(混合类型） division 7.0/4 is %.2f ",7.0/4); //4自动转换成float类型 return 0; }

把秒转换成分钟和秒 //把秒转换成分钟和秒 #include<stdio.h> #define SEC_PER_MIN 60 int main(void) { int sec,min,left; printf("convert seconds to minutes and seconds! "); printf("Enter the number of seconds (<=0) to quit): "); scanf("%d",&sec);//读入秒数 while(sec>0) { min=sec/SEC_PER_MIN;//截尾后得到的分钟数。 left=sec%SEC_PER_MIN;//剩下的秒数。 printf("%d seconds is %d minutes,%d seconds. ", sec,min,left); printf("Enter next value(<=0 to quit): "); scanf("%d",&sec); } printf("Done! "); return 0; }

后缀和前缀 #include<stdio.h> int main(void) { int a=1,b=1; int aplus,plusb; aplus=a++; plusb=++b; printf("a aplus b plusb. "); printf("%ld %5d %5d %5d ",a,aplus,b,plusb); return 0; } //输出结果为 2 1 2 2 //a++ 使用a的值之后改变a. //++a 先改变a的值，然后使用a

四种类型的语句 //四种类型的语句 #include<stdio.h> int main(void) //求出前20个整数的和 { int count,sum; //声明语句 count =0; //赋值语句 sum=0; while(count++<20) //while sum=sum+count; //语句 printf("sum=%d ",sum);//函数语句 return 0; }

定义一个有参数的函数 //定义一个有参数的函数 #include<stdio.h> void pound(int n);//函数声明（原型） int main(void) { int times=5; char ch='!'; float f=6.0; pound(times);//int 型参数 pound(ch);//char 参数自动转换成int类型 pound((int)f); return 0; } void pound(int n)//说明该函数接受一个int型参数 { while(n-->0) printf("#"); printf(" "); }

C 运算符、表达式和语句

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