【算法】大数相加

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX 100

void plus(char *a, char *b);

int main(void)
{
    char a[MAX], b[MAX];

    gets(a);
    gets(b);
    plus(a, b);
    return 0;
}

void plus(char *a, char *b)
{    
    char c[MAX+1];
    int len_a = strlen(a);
    int len_b = strlen(b);
    int i = len_a - 1; // 字符串a倒序
    int j = len_b - 1; // 字符串b倒序
    int k = 0; // 字符串c正序 c[k] = a[i] - b[j];
    int flag = 0; // 是否本次有进位,有的话在下一次循环加1；
    int x, y, z; // 相加的临时变量x = a[i], y = b[j], z = x- y

    while(i >= 0 || j >= 0)
    {
        if(i < 0)
            x = ‘0‘;
        else
            x = a[i];

        if(j < 0)
            y = ‘0‘;
        else
            y = b[j];

        z = x - ‘0‘ + y - ‘0‘;
        if(flag)
            z += 1;
        if(z > 9)
        {
            flag = 1;
            z = z % 10;
        }
        else
            flag = 0;
        c[k++] = z + ‘0‘;
        i--;
        j--;
    }
    

    if(flag)
        c[k++] = ‘1‘;
    c[k++] = ‘\0‘;
    

    for(int p = strlen(c) - 1; p>=0; p--)
    {
        printf("%c ", c[p]);
    }
    printf("\n");
}