C语言读取txt文件内容

C语言读取txt文件内容的几行代码备份，后面用到时直接复制粘贴。

char *readLine(FILE *fp, char *buffer, int *len)
{
    int ch;
    int i = 0;
    size_t buff_len = 0;

    buffer = (char *)malloc(buff_len + 1);
    if (!buffer)
        return NULL; // Out of memory

    while ((ch = fgetc(fp)) != 'n' && ch != EOF)
    {
        buff_len++;
        void *tmp = realloc(buffer, buff_len + 1);
        if (tmp == NULL)
        {
            free(buffer);
            return NULL; // Out of memory
        }
        buffer = (char *)tmp;

        buffer[i] = (char)ch;
        i++;
    }
    buffer[i] = '';

    *len = buff_len;

    // Detect end
    if (ch == EOF && (i == 0 || ferror(fp)))
    {
        free(buffer);
        return NULL;
    }
    return buffer;
}

int readLines(const char *fileName, char *lines[], int max_line)
{
    FILE *file = fopen(fileName, "r");
    char *s;
    int i = 0;
    int n = 0;
    while ((s = readLine(file, s, &n)) != NULL)
    {
        lines[i++] = s;
        if (i >= max_line)
            break;
    }
    return i;
}