谁能帮我看看阿...,

#include<stdio.h>
#include<string.h>
char a[50];
char b[50];
char res[100];
void multiply();

int main()
{
	scanf("%s%s",&a,&b);
	multiply();
	printf("%s\n",res);
	return 0;
}

void multiply()
{
	int len1=strlen(a);
	int len2=strlen(b);
	int i,j,mid,len,t;
	char temp;
	int up=0;
	mid=(len1+1)/2;
	for(i=0;i<mid;i++) 
	{
		temp=a[i];a[i]=a[len1-1-i];a[len1-1-i]=temp;
	}
	mid=(len2+1)/2;
	for(i=0;i<mid;i++)
	{
		temp=b[i];b[i]=b[len2-1-i];b[len2-1-i]=temp;
	}
	for(i=0;i<len1;i++)
	{
		for(j=0;j<len2;j++)
		{
			t=(a[i]-'0')*(b[j]-'0')+up;
			if(res[i+j]=='\0')  t+=(int)res[i+j];
			else  t+=(int)(res[i+j]-'0');
			if(t>9)  up=temp/10;
			else up=0;
			res[i+j]='0'+t%10;
		}
		if(up!=0)
		{
			res[i+j]=up+'0';
			up=0;
		}
	}
	len=strlen(res);
	mid=(len+1)/2;
	for(i=0;i<mid;i++)
	{
		temp=res[i];res[i]=res[len-1-i];res[len-1-i]=temp;
	}
}