Figure out "last item that meets the criteria" and "first item that does not meet the criteria"
#include<stdio.h>
void main(){
int i,n,r,a[33];
while(scanf("%d%d",&n,&r)!=EOF){
i=0;
if(n<0){
printf("-");
n=-n;
}
while(n){
//=while(n!=0) 等于0时跳出，假设一共C个
a[i]=n%r;//a[0],a[1],a[2],……,a[C-1]
n/=r;
i++;//最后i=C
}
while(i--){
//a[C-1],a[C-2],……,a[3],a[2],a[1],a[0] while(i--)是先使用再自减，所以是判断的是C>0? C-1>0? 1>0?但是使用的是C-1,c-2 0
if(a[i]<10)
printf("%d",a[i]);
else
printf("%c",a[i]-10+'A');
}
printf("\n");
}
}
#include<stdio.h>
void main(){
int i,r,n,a[33];
while(~scanf("%d%d",&n,&r)){
if(n<0){
printf("-");
n=-n;
}
for(i=0;n;i++){
a[i]=n%r;
n/=r;
}
for(i-=1;i+1;i--){
if(a[i]<10)
printf("%d",a[i]);
else
printf("%c",a[i]-10+'A');
}
printf("\n");
}
}
Summary
//The specific process of while(n–) is to judge whether it is zero from n to 1, and the value of n is used from n-1 to 0 below. A total of n cycles. It is equivalent to for(i=n-1;i+1;i--)
//while(n) is equivalent to for(;n;)
//while() for() In many cases, the difference lies in whether it is the current item or the previous item One item is still the next item
//i++ i–Increment and decrement operators are used first and then add, use first and then subtract