求1~n中有多少个9
不断取低位和9比较
/*求1~n中有多少个9*/
#include <stdio.h>
int main ()
{
printf ("Function : Numbers of 9.\n");
int count, i, num, temp, n;
printf ("Please input a number.\n");
scanf ("%d",&n);
count = 0;
for (i = 1;i <= n; i++)
{
num = i;
while (num)
{
temp = num % 10; //取低位，判断是否是9
num /= 10; //去除低位
if (temp == 9)
count++;
}
}
printf ("The number of 9 between 1 and n are : %d\n",count);
return 0;
}
