初学C语言常用简单程序代码

1、初学C语言常用简单程序代码素数的筛选#include <stdio.h> #include <math.h>#define N 1000 int main(int argc, char* argv) int i,j,numN; for(i=0;i<N;i+) numi=i+1; for(i=1;i<(int)sqrt(double)N);i+) if(numi) for(j=i+1;j<N;j+) if(numj) if(numj%numi=0) numj=0; for(i=1;i<N;i+) if(numi) printf(" %d&

2、quot;,numi); return 0;输出时分秒#include <stdio.h>main()int x,s,t,d;scanf("%d",&x);s=x%60;t=(x/60)%60;d=(x/60)/60;printf("%d时%d分%d秒",d,t,s);三个数的交换#include <stdio.h> void main()int a,b,c,t;scanf("%d%d%d",&a,&b,&c);printf("The original number:a

3、=%d,b=%d,c=%dn",a,b,c); t=a,a=b,b=t; t=a,a=c,c=t;printf("after swap:a=%d,b=%d,c=%d",a,b,c);switch语句的运用#include <stdio.h>main()int a,m;printf("please input a number:");scanf("%d",&a);switch(a/10)case 10:case 9: m=5; break;case 8: m=4; break;case 7:m=3; bre

4、ak;case 6:m=2; break;default:m=1;printf("m=%d",m);判断奇数和偶数#include <stdio.h>main()int x;printf("Please input a number: ");scanf("%d",&x);if(x%2=0)printf("this is a oushu!");elseprintf("this is a jishu!");小写改大写，若是大写则不变include <stdio.h>m

5、ain() char c1,c2; printf("Input a lettern"); scanf("%c",&c1); c2=('a'<=c1&&c1<='z')?(c1-'a'+'A'):c1; printf("%c",c2); getchar(); return 0;输入一个数，输出这个数是几位数#include <stdio.h>main()int x,n;printf("please input a n

6、umber:");scanf("%d",&x);n=0;while(x!=0)x=x/10;n+;printf("%d",n);输入一个数，判断它是几位数，然后逆序输出#include<stdio.h> int main() int num; int len = 0; int temp =0; printf("Please input a number:n"); scanf("%d",&num); while(num % 10)!=0) temp = temp*10+(num%

7、10); len+; num = num/10; printf("length = %dn",len); printf("Reverse is %d", temp); 打印水仙花数#include <stdio.h>main()int x, a,b,c;for(x=100;x<=999;x+)a=x%10;b=(x/10)%10;c=x/100;if(x=a*a*a+b*b*b+c*c*c)printf("%5d",x);printf("n");判断闰年#include "stdio.h

8、"main()int k,flag,n=0; for(k=1980;k<=2880;k+) flag=(k%4=0)&&(k%100!=0)|(k%400=0); if(flag) printf("%5d",k); n+; if(n%10=0) printf("n"); printf("n");求1-3+5-7.-99+101的值#include <stdio.h>main()int sum,i,t;sum=1;t=1;for(i=3;i<=101;i=i+2)t=-t;sum=sum

9、+t*i;printf("sum=%d",sum);求前n项和#include <stdio.h>main()float s,t;int n,i,fz,fm;s=0;fz=2;fm=1;printf("Enter n:");scanf("%d",&n);for(i=1;i<=n;i+) t=(1.0*fz)/fm;s=s+t; fz=fz+fm; fm=fz-fm; printf("s=%fn",s);开发一个程序求全班学生某门课的平均成绩，要求程序每次运行时班级人数可为任意/*用标记值来

10、指示数据输入的结束*/#include <stdio.h>main()float average,total;int counter,score;total=0.0;counter=0;printf("输入成绩,-1表示结束:");scanf("%d",&score);while(score!=-1) /*用-1表示输入的结束,同时循环输入分数*/total=total+score;counter+;printf("输入下一个成绩,-1表示输入结束:");scanf("%d",&scor

11、e);if(counter!=0)average=total/counter;printf("全班平均成绩为：%.2fn",average);elseprintf("没有输入成绩n");return 0;求二元一次方程的根#include <stdio.h>#include <math.h>main()float a=4,b=-40,c=91;float x1,x2;float delta;delta=sqrt(b*b-4.0*a*c);x1=(-b+delta)/(2.0*a);x2=(-b-delta)/(2.0*a);pri

12、ntf("x1=%f x2=%fn",x1,x2);if语句的运用#include <stdio.h>main()int a,b,c,s,w,t;s=w=t=0;a=-1;b=c=3;if(c>0)s=a+b;if(a<=0)if(b>0)if(c<=0)w=a-b;elseif(c>0)w=a-b;elset=c;printf("s=%d, w=%d,t=%d",s,w,t);输入学生的生日，输出他的实足年龄#include <stdio.h>main()int y0,m0,d0,y1,m1,d1,

13、age;printf("nplease input birthday (yyyy/mm/dd):");scanf("%d/%d/%d ",&y0,&m0,&d0);printf("nplease input current day(yyyy/mm/dd):");scanf("%d/%d/%d ",&y1,&m1,&d1);if(m1>m0) | (m1=m0 && d1>=d0)age=y1-y0;elseage=y1-y0-1;print

14、f("age=%d n",age);指针变量作为函数参数，实现两数的交换#include <stdio.h>void sswap(int *x,int *y);main()int a=10,b=20;printf("before swap:a=%d,b=%dn",a,b);sswap(&a,&b);printf("after swap:a=%d,b=%dn",a,b);void sswap(int *x,int *y)int t;t=*x;*x=*y;*y=t;通过函数调用输出两个实型数中最大的一个#inc

15、lude <stdio.h>float *f(float *px,float *py)if(*px>*py)return px;return py;main()float x=10.0,y=20.0,*a=&x,*b=&y;printf("*a=%f,*b=%f,max=%fn",*a,*b,*f(a,b);计算并输出一个数组中所有元素的和，最大值，最小值，值为奇数的元素个数编写一个函数，将一个字符串中的字符全部转成大写#include <stdio.h>void Lower2Upper(char *str)char *p=st

16、r;while(*p!=0)if(*p<='z'&&*p>='a')*p=*p-32;p+;main()char s10="Hello!"int i;Lower2Upper(s);for(i=0;i<10;i+)printf("%c",si);计算一个字符在一个字符串中出现的次数#include <stdio.h>int count(char ch,char *str)char *p=str;int num=0;while(*p!='0')if(*p+=ch)n

17、um+; return num;main()char ah='a'char s="haowareayou" printf("the number is:");printf("%dn",count('a',s);删除一维数组中所有相同的数#include <stdio.h>void unique(int *a,int *n)int k=1;int i,m;m=a0;for(i=0;i<*n;i+)if(ai>m)ak+=ai;m=ai;*n=k;main()int a10;int

18、n=10,i;printf("input a list number:");for(i=0;i<n;i+)scanf("%d",&ai); printf("Before delete:.n");for(i=0;i<n;i+)printf("%d",ai);unique(a,&n);printf("after delete.n");for(i=0;i<n;i+)printf("%d",ai);printf("n");将字符串

19、按字典顺序输出#include <stdio.h>#include <string.h>#define N 5void sort(char *name,int n);void prn(char *name,int n);void main()char *name="China","America","Australia","France","German"sort(name,N);prn(name,N);void sort(char *name,int n)char *pt;int i,j,k;for(i=0;i<n-1;i+)k=i;for(j=i+1;j<n;j+)if(strcmp(namek,namej)>0)k=j;if(k!=i)pt=namei;namei=namek;namek=