1.
#include <stdio.h>
void main(){
int a,n,Sn=0,sum=0,item=0;
printf("please input a number:");
scanf("%d",&a);
printf("please input n number:");
scanf("%d",&n);
int s=0;
while(n>0){
Sn=a;
item+=Sn;
sum+=item;
a=a*10;
n--;
}
printf("%d\n",sum);
}
2.
#include <stdio.h>
void main(){
int a,n,i,sum=0,item=0;
printf("请输入a和n:\n");
scanf("%d%d",&a,&n);
for(i=1;i<=n;i++){
item=item*10+a;
sum+=item;
}
printf("%d\n",sum);
}
总结:
当 a=2,n=4时
进入for循环后,
依次执行:
item=a sum = 2
item=item*10+a(2*10+2) sum=2+22
item=item*10+a(22*10+2) sum=2+22+222
item=item*10+a(222*10+2) sum=2+22+222+2222