高精度加法C语言

#include <stdio.h>
#include <string.h>
#define N 100010

void add(char str1[], char str2[], char add_high[])
{
    int index = 0;
    int len1 = strlen(str1);
    int len2 = strlen(str2);
    int a[N] = {0};
    int b[N] = {0};
    int res[N] = {0};
    // 1. 将字符数组转换成整数数组，第0位存储个位数字
    for (int i = 0; i < len1; i ++ )
        a[i] = str1[len1 - 1 - i] - '0';
    for (int i = 0; i < len2; i ++ )
        b[i] = str2[len2 - 1 - i] - '0';
    // 2. 加法过程
    int t = 0;
    for (int i = 0; i < len1 || i < len2; i ++ )
    {
        if (i < len1) t += a[i];
        if (i < len2) t += b[i];
        res[index ++] = t % 10;
        t /= 10;
    }
    // 如果还有进位，补最高位
    if (t != 0)
        res[index ++] = t;
    // 去除前导0
    int zero_index = 1;
    int happy = 0;
    for (int i = index - 1; i >= 0; i -- )
    {
        if (res[i] == 0 && zero_index == 1)
            continue;
        else
        {
            zero_index = 0; // 不是前导0
            add_high[happy ++] = res[i] + '0';
        }
    }
    if (zero_index == 1)
        strcpy(add_high, "0");
}

int main()
{
    char str1[N] = "";
    char str2[N] = "";
    char add_high[N] = "";
    scanf("%s", str1);
    scanf("%s", str2);
    add(str1, str2, add_high);
    puts(add_high);
    return 0;
}