大数相乘

void Mult(char fal[],char a[],char b[])  
{  
    int i,j,len1,len2,afal[210];  
    len1=strlen(a);  
    len2=strlen(b);  
    memset(fal,0,sizeof(fal));  
    memset(afal,0,sizeof(afal));  
    for(i=len1-1;i>=0;i--)  
    {  
        for(j=len2-1;j>=0;j--)  
            afal[len1+len2-i-j-2]+=(a[i]-'0')*(b[j]-'0');  
    }  
      
    for(i=0;i<len1+len2;i++)  
    {  
        if(afal[i]>9)  
        {  
            afal[i+1]+=afal[i]/10;  
            afal[i]=afal[i]%10;  
        }  
    }  
    bool t=0;  
    j=0;  
    for(i=len1+len2;i>=0;i--)  
    {  
        if(t)  
            fal[j++]=afal[i]+'0';  
        else if(afal[i])  
        {  
            fal[j++]=afal[i]+'0';  
            t=1;  
        }  
    }  
    fal[j]=0;  
    if(t==0) strcpy(fal,"0");  
}