第七次作业

1. 输出以下图形

 

 

*

**

***

****

*****

 

 

*******

*****

***

*

#include <stdio.h>

main(){

         int i,j;

         for (i=1;i<=5;i++)

         {

                  for (j=1;j<=9-2*i;j++)

                  printf("*");

         printf("\n");

         }

}

 

 

 

#include <stdio.h>

main(){

         int i,j;

         for (i=1;i<=4;i++)

         {

                  for (j=1;j<=9-2*i;j++)

                  printf("*");

         printf("\n");

         }

}

 

 

 

2 .练习册 P64  8

#include <stdio.h>

main(){

         int x,y;

         for (x=0;x<=35;x++)

         {

                  y=35-x;

                  if (2*x+4*y==94)

                  printf("有%d只鸡\n有%d只兔子",x,y);

         }

}

 

 

 

3. 练习册 P64  9

#include <stdio.h>

main(){

int i,j;

printf("九九乘法表\n");

for(i=1;i<=9;i++)

{

         for(j=1;j<=i;j++)

                  printf("%2d*%2d=%2d",j,i,i*j);

         printf("\n");

}

 

}

 

 

 

 

4.输入一个数判断是不是质数（质数是只能被1和自身整除的数）

#include<stdio.h>

main(){

int i,n;

printf("请输入n:");

scanf("%d",&n);i=2;

while(i<n)

{

if(n%i==0)break;i++;

}

if(i==n)

printf("YES!\n",n);

else

printf("NO!\n",n);

}