5📌

//用while语句
int main() {
    int n;
    int count=0;
    int factorial=1;
    printf("Enter the number of factorial: ");
    scanf("%d", &n);
    while(count<n) {
        count ++;
        factorial=factorial*count;
    }

    printf("The factorial is %d",factorial);
    return 0;
}
//用for语句
int main() {

 int n;
 int fact=1;
 int i=1;
 printf("Enter the number of factorial: ");
 scanf("%d", &n);
//①从1开始乘
for(i=1;i<=n;i++) {
 fact=fact*i;
}
//②从n开始乘
for(i=n;i>=2;i--){
    fact=fact*i
}

 printf("The factorial of %d is %d",n,fact);

 return 0;
}

for (i=1① ; i<=n ②; i++③ )
/*
①初始条件
②循环继续的条件
③循环每轮要做的事情
 */

int main(){

 int x;
 int i;
 int isPrime=1;
 scanf("%d",&x);

 for(i=2;i<x;i++) {
    if(x%i==0) {
     isPrime=0;
     break;//跳出整个循环
    }
 }

if(isPrime==1) {
 printf("yes");
}else {
 printf("no");
}

return 0;
}

int main(){

 int x;
 int i;



 for (x=2;x<100;x++) {
  int isPrime=1;
       for(i=2;i<x;i++) {
          if(x%i==0) {
           isPrime=0;
           break;
          }
       }

       if(isPrime==1) {
        printf("%d\n",x);
       }

 }
return 0;
}

/*13425/10000->1
13425%10000->3425
10000/10->1000

3425/1000->3
3425%1000->425
1000/10->100

^^^^
*/

int main() {
    int x=13425;
     int div=10000;
     int n;
     while(x>0) {

          n=x/div;
          x=x%div;
          div=div/10;

          printf("%d ",n);
         }

 return 0;
}

//////////////////////////////
//改进：可输入数字自动判断位数//
/////////////////////////////
int main() {

 int x;
 int count=0;
 printf("Enter a number: ");
 scanf("%d", &x);
//统计位数
 int num=x;
 while(x>0) {
  x=x/10;
  count+=1;
 }
//分离数位
 int div=pow(10,count-1);
 int n=0;
 while(num>0) {

      n=num/div;
      num=num%div;
      div=div/10;

  printf("%d ",n);
 }


 return 0;
}

int main() {
    int a,b;
    int min;
    printf("Enter two numbers:");
    scanf("%d%d",&a,&b);

    if(a>b) {
        min=b;
    }else {min=a;}


    int i=1;
    int ret=0;
    for(i=1;i<min;i++) {
        if(a%i==0) {
            if(b%i==0) {
                ret=i;
            }
        }
        if(b%i==0) {
        }

    }

    printf("GCS is %d",ret);

    return 0;
}

/*如果b等于0，计算结束，a就是最大公约数；
否则，计算a除以b的余数，让a等于b,而b等于那个余数
回到第一步*/

int main() {

    int a,b;
    printf("Enter two numbers:\n");
    scanf("%d %d",&a,&b);

    if(b==0) {
        printf("%d",a);
    }
    else {
        while(b!=0) {

            int t = a % b;
            a=b;
            b=t;
        }
        printf("%d",a);
    }

    return 0;
}