12-21日 刘阳阳

1. 写一个函数返回参数值为1的个数

比如：15       0000 1111       4个1。

自己想法；

#include <stdio.h>int fuc(int n){int a[30];int i=0,m;int count=0;    while(n!=0){m=n%2;n=n/2;a[i]=m;i++;}while (i>0){printf("%d",a[--i]);}for (i=0;i<8;i++){if (a[i]==1){count++;}}return count;}int main(){int p,num;printf("请输入一个数\n");scanf("%d",&p);num=fuc(p);printf("\n");printf("%d\n",num);}

改进后

int fuc(int n){int m;int count=0;    while(n!=0){m=n%2;n=n/2;if (m==1){count++;}}return count;}int main(){int p,num;printf("请输入一个数\n");scanf("%d",&p);num=fuc(p);printf("%d\n",num);}

2. 求100~200之间的素数

#include<stdio.h>int main(){int a,i;for (a=100;a<=200;a++){for(i=2;i<=a;i++){if(a%i==0)break;}if (a==i){     printf("%d ",a);}}return 0;}

3. 输出乘法口诀表

#include <stdio.h>int main(){int i,n,sum;for (i=1;i<=9;i++){for(n=1;n<=9;n++){sum=i*n;printf("%d*%d=%d \n",i,n,sum);//printf("%d ",sum);}}return 0;}

4.不允许创建临时变量，交换两个数的内容 

#include <stdio.h>int main(){int a=10,b=20;a=a+10;b=a-10;printf("%d %d\n",a,b);return 0;}

5. 求10个数中最大值

#include <stdio.h>int main(){int i,j,max;//int a[10]={12,23,2,34,5,6,7,8,45,70};int a[10];for (i=0;i<=9;i++){scanf("%d",&a[i]);}for (i=0;i<=9;i++){for(j=0;j<=9;j++){if (a[i]>a[j]){max=a[i];}else{max=a[j];}}}printf("最大值是%d\n",max);return 0;}