C語言整數轉字符串（itoa()函數）小練習

#include <stdio.h>

void itoa(int ,char *);
void reverse(char *);

/*itoa 函數： 將數字轉換成字符串並保存到S中*/
void itoa(int n, char s[])
{
  int i,sign;

  if((sign = n) < 0)
	  n = -n;
  i = 0;
  do
  {
    s[i++] = n % 10 + '0';
  }while((n /= 10) > 0);

  if(sign < 0)
	  s[i++] = '-';
  s[i] = '\0';

  reverse(s);

}

/*reverse 函數：字符串反轉（指針方法不安全）*/
void reverse(char *s)
{
  int len = strlen(s);
 
  char *ptr1,*ptr2;

  ptr1 = s;
  ptr2 = s + len - 1;

  while(ptr1 != ptr2)
  {
    char temp;
	temp = *ptr1;
	*ptr1 = *ptr2;
	*ptr2 = temp;
	ptr1++;
	if(ptr1 == ptr2)
		break;
	else
		ptr2--;
  }
  
}

/*《The C programming language(second edition)》中實現int型轉字符串練習*/
int main()
{ int a;
  char s[20];
  printf("please input a int :\n");
  scanf("%d",&a);
  itoa(a,s);
  printf("The int is %s\n",s);

  return 0;
}