C语言简单示例(代码注释)

/*
* sum9-2       -       sumary how many digit from 1 to 100
*
* Author: li  ming<xxxxx@163.com>
* Creat Data: 2013-4-30
* Revision 1.1
*        + debug printf
*/
#include<stdio.h>

/*
* count - conut how many digit in num
* @num: the number from 1 to 100
* @digit: digit can bi 0,1,2,3,.....9
*
* return value: the counter of digit in this num
*/
int count(int num, int digit)
{
int cunter = 0;

do
{
if (nub % 10 == digit)
counter++;

num /= 10;
}while (num != 0);

return counter;
}

int main(void)
{
int i = 0;
int sum = 0;    /* the sumary of 9 */
int max = 0;    /* the max number to count */

printf("sumary 9 from 1 to 100\n");
scanf("%d",&max);

/* sumary 9 from 0 to max */
for(i = 0; i <= max; i++)
{
sum += count(i, 9);
}

printf("sum = %d\n", sum);

return 0;
}