初学C语言常用简单程序代码

初学C语言常用简单程序代码素数的筛选

#include

#include

#define N 1000

int main(int argc, char* argv[])

{

int i,j,num[N];

for(i=0;i

num[i]=i+1;

for(i=1;i<(int)sqrt((double)N);i++)

{

if(num[i])

{

for(j=i+1;j

{

if(num[j])

if(num[j]%num[i]==0)

num[j]=0;

}

}

}

for(i=1;i

if(num[i])

printf(" %d",num[i]);

return 0;

}

输出时分秒

#include

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

void main()

{

int a,b,c,t;

scanf("%d%d%d",&a,&b,&c);

printf("The original number:a=%d,b=%d,c=%d\n",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

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; break;

case 6:m=2; break;

default:m=1;

}

printf("m=%d",m);

}

判断奇数和偶数

#include

main()

{

int x;

printf("Please input a number: ");

scanf("%d",&x);

if(x%2==0)

printf("this is a oushu!");

else

printf("this is a jishu!");

}

小写改大写，若是大写则不变

include

main()

{

char c1,c2;

printf("Input a letter\n");

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

main()

{

int x,n;

printf("please input a number:");

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

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%10);

len++;

num = num/10;

}

printf("length = %d\n",len);

printf("Reverse is %d", temp); }

打印水仙花数

#include

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"

main()

{

int k,flag,n=0;

for(k=1980;k<=2880;k++)