C语言初学者的几个经典习题

1、1 .求两个数的最小公倍数：#include<>voidmain()inta,b,num1,num2,temp;printf("请输入两个数：n");scanf("%d%d",&num1,&num2);if(num1<num2)temp=num1;num1=num2;num2=temp;a=num1;b=num2;while(b!=0)temp=a%b;a=b;b=temp;printf("最小公倍数为：%dn",num1*num2/a);2 .判断某一天是一年的第多少天：#include<&g

2、t;intsum_day(intyear,intmonth,intday);voidmain()intyear,month,day;intdays;printf("请输入要查询的年月日n");scanf("%d%d%d",&year,&month,&day);days=sum_day(year,month,day);printf("该天是d天n",days);inttab13=0,31,28,31,30,31,30,31,31,30,31,30,31;intsum_day(intyear,intmonth,in

3、tday)inti,days=0;if(year%4=0&&year%100!=0|year%400=0)tab2=29;for(i=1;i<month;i+)days+=tabi;days+=day;returndays;3 .判断一个数是不是素数：#include<>intisprime(inta);voidmain()intx;printf("请输入要判断的正整数:n");scanf("%d",&x);if(isprime(x)printf("%d是素数n",x);elseprintf(

4、"%d不是素数n",x);4 .计算矩阵对角线元素之和：#include<>voidmain()inti,j,a55,sum=0,n=5;for(i=0;i<5;i+)printf("行%d:",j);for(j=0;j<5;j+)scanf("%d",&aij);if(i=j)sum+=aij;if(i+j=4)sum+=aij;sum-=a22;5 .斐波拉契数列：(1)#include<>voidmain()intA20;inti;A0=1;A1=1;for(i=2;i<20;i

5、+)Ai=Ai-1+Ai-2;for(i=0;i<20;i+)printf("%d",Ai);if(i+1)%5=0)printf("n");(2)#include<>intfibo(intn);voidmain()inti;for(i=1;i<=20;i+)printf("%d",fibo(i);if(i%5=0)printf("n");intfibo(intn)intk;if(n=1)k=1;elseif(n=2)k=1;elsek=fibo(n-1)+fibo(n-2);returnk

6、;6 .查询数字：#include<>voidmain()inta10,left=0,right=10,mid,i,j;printf("请按从小到大的顺序输入被查询序列的10个数:n");for(i=0;i<=9;i+)scanf("%d",&ai);printf("请输入待查询的整数:n");scanf("%d",&j);while(left<=right)mid=(left+right)/2;if(amid=j)printf("待查询数字在d位",mid+1);break;elseif(amid>j)right=mid-1;elseif(amid<j)left=mid+1;if(left>right)printf("待查询数字不在此序列");7 .统计字符串：#include<>intp(chara,charb)inti=0,j=0,k=0;for(i=0;ai;i+)j=i;for(k=0;aj=bk&&bk&&aj;j+,k+)