C++ 为什么realloc函数在此代码中修改变量

我正在学习C语言，并试图解决LeetCode的练习412.

我的问题是，当x是127时，当执行代码的第64行时，x返回到124值，程序进入无限循环.

第64行

output = realloc(output, sizeof(char *) * x);

我的整个代码:

#include <stdio.h>
#include <stdlib.h>

char **fizzBuzz(int n) {
    int x, temp, x_aux, cont;
    char **output;
    output = NULL;
    for (x = 1; x <= n; x++)
    {
        if (x % 3 == 0)
        {
            if (x % 5 == 0)
            {
                //answer[i] == "FizzBuzz" if i is divisible by 3 and 5.
                output = realloc(output, sizeof(char *) * x);
                output[x-1] = malloc(sizeof(char) * 9);
                output[x-1][0] = 'F';
                output[x-1][1] = 'i';
                output[x-1][2] = 'z';
                output[x-1][3] = 'z';
                output[x-1][4] = 'B';
                output[x-1][5] = 'u';
                output[x-1][6] = 'z';
                output[x-1][7] = 'z';
                output[x-1][8] = 0;
            }
            else
            {
                //answer[i] == "Fizz" if i is divisible by 3.
                output = realloc(output, sizeof(char *) * x);
                output[x-1] = malloc(sizeof(char) * 5);
                output[x-1][0] = 'F';
                output[x-1][1] = 'i';
                output[x-1][2] = 'z';
                output[x-1][3] = 'z';
                output[x-1][4] = 0;
            }
        }
        else if (x % 5 == 0)
        {
            //answer[i] == "Buzz" if i is divisible by 5.
            output = realloc(output, sizeof(char *) * x);
            output[x-1] = malloc(sizeof(char) * 5);
            output[x-1][0] = 'B';
            output[x-1][1] = 'u';
            output[x-1][2] = 'z';
            output[x-1][3] = 'z';
            output[x-1][4] = 0;
        }
        else
        {
            //answer[i] == i (as a string) if none of the above conditions are true.
            output = realloc(output, sizeof(char *) * x);
            cont = 1;
            x_aux = x;
            while (x_aux >= 10)
            {
                temp = x_aux % 10;
                output[x-1] = realloc(output[x-1], sizeof(char) * cont);
                output[x-1][cont-1] = temp + '0';
                x_aux = (int)x_aux / 10;
                cont += 1;
            }
            output[x-1] = realloc(output[x-1], sizeof(char) * (cont+1));
            output[x-1][cont-1] = x_aux + '0';
            output[x-1][cont] = 0;
        }
    }
    return output;
}

int main()
{
    char **string;
    int num = 134;
    int m, y;
    string = fizzBuzz(num);

    for (m = 0; m < num; m++)
    {
        for (y = 0; string[m][y] != 0; y++)
            printf("%c", (char)string[m][y]);
        printf("\n");
    }

    return 0;
}

谢谢！！

我知道解决方案的逻辑不是x%正确的，但我想知道x更改值(127到124)会发生什么.