第四章例4-3

#include<stdio.h>
#include<math.h>
int main(void)
{
 int count,number;

 count=0;
 printf("Enter a number:");
 scanf("%d",&number);
 if(number<0)number=-number;
 do{
  number=number/10;
  count++;
 }while(number!=0);
 printf("It contains %d digits.\n",count);

 return 0;
}