C++ 如何将字符**传递给需要常量字符指针的常量数组的函数

如下所示，我希望将一个由char **x定义的变量作为只读传递给一个函数.

一本参考书显示了线性搜索源代码，它通过将变量作为由const int a[]定义的临时参数传递给search函数来对由char *x定义的变量执行线性搜索.

所以我突然想到了一个 idea ，如果是弦呢？然后我编写了下面的代码.

GCC、叮当和MSVC的分析可以找到here个.

// Linear Search

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

int scanf_s(const char *format ,...); // for gcc and clang environment
// int search(const char **a, int n, char *key) {       //※[1]not allowed in c lang specification⇒NG
// int search(char * const *a, int n, char *key) {      //※[2]⇒NG
// int search(const char * const *a, int n, char *key) {    //※[3]warning occured in gcc and clang！！
// int search(char const * const *a, int n, char *key) {//※[4]same as above
// int search(const char * const a[], int n, char *key) {//※[5]same as above
// int search(const char *a[], int n, char *key) {      //※[6]I thought this was ok, but warning occured in gcc and clang！！
int search(char **a, int n, char *key) {            //in conclusion, gcc,clang and MSVC only allowing this!!
    int i = 0;

    for (i = 0; i < n; i++) {
        if (strcmp(a[i], key) == 0)
            return i;
    }
    return -1;

    /* or while style!! the reference book shows this style!!
    while (1) {
        if (i == n)
            return -1;
        if (strcmp(a[i], key) == 0)
            return i;
        i++;
    }
    */
}

int main(void) {
    char **x;
    char *ky;
    int nx;
    int idx;
    int i;

    puts("Linear Search");
    printf("How many Elements??:");
    scanf_s("%d", &nx);
    
    x = malloc(sizeof(char*) * nx);
    if (x == NULL) {
        printf("Pointer to Pointer x malloc failed!!\n");
        exit(EXIT_FAILURE);
    }

    for (i = 0; i < nx; i++) {
        printf("x[%d]:", i);
        x[i] = malloc(sizeof(char) * 35);
        if (x[i] == NULL) {
            printf("Pointer Array x[] malloc failed!!\n", i);
            exit(EXIT_FAILURE);
        }
        scanf_s("%s", x[i], 35);
    }

    printf("Target Value:");
    ky = malloc(sizeof(char) * 35);
    if (x == NULL) {
        printf("target value malloc failed!!\n");
        exit(EXIT_FAILURE);
    }
    // Or
    // ky = calloc(35, sizeof(char));
    scanf_s("%s", ky, 35);

    idx = search(x, nx, ky);

    if (idx == -1)
        puts("no target value.");
    else
        printf("%s is in x[%d]！！\n", ky, idx);

    free(ky);
    for (i = 0; i < nx; i++) {
        free(x[i]);
    }
    free(x);
    system("pause");
    return 0;
}

代码为const的代码会使GCC和Clang显示警告，尽管msvc可以在没有任何警告的情况下进行编译，如注释(※[1]~[6])所示.

那么，如何在search函数必须接受由char **x定义的变量作为只读参数的情况下编写代码呢？