不调用C库，C语言数字转字符串

#include 



char *itoa(char *p, int n);

int main(int argc, char *argv[])
{
        int n;
        char  s[50], * r;

        printf("input:");
        scanf("%d", &n);

        r = itoa(s, n);

        puts(r);
        puts(s);

        return 0;
}

char *itoa(char *p, int n)
{
        int r, i = 0, j;
        //static char p[50];
        //为来得到我们的每一位的数字，好加48转字符串
        while (n) {
                r = n % 10;
                n /= 10;
                p[i] = r + '0';
                i++;
        }
        p[i] = '';
        //下面主要就是交换一下位置，4321,变成1234
        j = i-1;
        i = 0;

        while (i < j) {
                r = p[i];
                p[i] = p[j];
                p[j] = r;
                i++;
                j--;
        }

        return p;
}