新手，轻喷

#include <stdio.h> 
#include <string.h>
char a[1005];
char b[1005];
char c[1005];
void reverse (char * a, int len)//逆置 
{
	for (int i = 0; i < len/2; i++)
	{
		char temp = a[i];
		a[i] = a[len - i - 1];
		a[len - i - 1] = temp;
		
	}
}
int addzero(char * a, char * b, int len_a, int len_b)//较小数字后面添0 
{
	int len;
	if (len_a > len_b)
		{
			len = len_a;
			for (int i = len_b; i < len; i ++)
				b[i] = '0';
		}
			
		else
		{
			len = len_b;
			for (int i = len_a; i < len; i ++)
				a[i] = '0';
		} 
		return len;
}
int main ()
{
	while (scanf ("%s%s", a, b) != EOF)
	{
		int len_a = strlen(a);
		int len_b = strlen(b);
		int len;
		reverse (a, len_a);
		reverse (b, len_b);//逆置 
		len = addzero (a, b, len_a, len_b);
		int carry = 0;
		for (int i = 0; i < len; i ++)//相加 
		{
			c[i] = (a[i] - '0' + b[i] - '0' + carry) % 10 + '0';
			carry = (a[i] - '0' + b[i] - '0' + carry) / 10 ;
		}
		int len_c;
...