大数运算

#include<stdio.h>
#include<string.h>
int main()
{
int i,j;
int num1[100],num2[100],num3[200];
int index;
int over = 0;//over表示要仅为的数值 
char str1[100],str2[100];
int temp;
scanf("%s",str1);
scanf("%s",str2);
index = 0;
for(i = strlen(str1) - 1;i >= 0;i --){
num1[index] = str1[i] - '0';
index ++;
}
printf("%d\n",strlen(str1));
index = 0;
for(i = strlen(str2) - 1;i >= 0;i --){
num2[index] = str2[i] - '0';
index ++;
}
index = 0;
while(index < strlen(str1) && index < strlen(str2)){
temp = num1[index] + num2[index] + over;
num3[index] = temp % 10;
over = temp / 10;
index ++;
}
if(index == strlen(str1) && index < strlen(str2)){
for(j = index;j < strlen(str2);j ++){
num3[j] = (num2[j] + over) % 10;
over = (num2[j] + over) / 10;
index ++;
}
}
if(index == strlen(str2) && index < strlen(str1)){
for(j = index;j < strlen(str1);j ++){
num3[j] = (num1[j] + over) % 10;
over = (num1[j] + over) / 10;
index ++;
}
}
if(over){
num3[index] = over;
index ++;
}
for(i = index - 1;i >= 0;i --)
printf("%d",num3[i]);
putchar('\n');
return 0;
}