大数相加

#include <stdio.h>
#include <malloc.h>
#include <string.h>

#define N 100

int main()
{
	int i;
	bool flag = false;
	char s1[N],s2[N];
	printf("输入被加数:\n");
	scanf("%s",s1);
	printf("输入加数:\n");
	scanf("%s",s2);
	int len1 = strlen(s1);
	int len2 = strlen(s2);
	int len = (len1>len2 ? len1:len2)+1;
	char *a = (char*)malloc(sizeof(char)*len1);
	char *b = (char*)malloc(sizeof(char)*len2);
	char *c = (char*)malloc(sizeof(char)*len);
	memset(c,len);
	for(i=0;i<len1;i++)
		a[i] = s1[len1-1-i]-'0';
	for(i=0;i<len2;i++)
		b[i] = s2[len2-1-i]-'0';
	if(len1>=len2)
	{
		for(i=0;i<len2;i++)
			c[i] = a[i]+b[i];
		for(i=len2;i<len1;i++)
			c[i] = a[i];
	}
	else
	{
		for(i=0;i<len1;i++)
			c[i] = a[i]+b[i];
		for(i=len1;i<len2;i++)
			c[i] = b[i];
	}
	for(i=0;i<len;i++)
	{
		if(c[i]>9)
		{
			c[i+1] += c[i]/10;
			c[i] = c[i]%10;
		}
	}
	printf("大数相加结果为:\n");
	for(i=len-1;i>=0;i--)
	{
		if(flag)
		{
			c[i]+='0';
			printf("%c",c[i]);
		}
		else if(c[i]!=0)
		{
			flag = true;
			c[i]+='0';
			printf("%c",c[i]);
		}
	}
	printf("\n");
	free(a);
	free(b);
	free(c);
	a=NULL;
	b=NULL;
	c=NULL;
	return 0;
}