1仿滔、實(shí)現(xiàn)

  /// is_array
  template<typename>
    struct is_array
    : public false_type { };

  template<typename _Tp, std::size_t _Size>
    struct is_array<_Tp[_Size]>
    : public true_type { };

  template<typename _Tp>
    struct is_array<_Tp[]>
    : public true_type { };

2拳昌、demo code

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

using std::cout;
using std::endl;
using std::system;
using std::string;

void exec_my_cmd(const string cmd) {  
    FILE *fp;  
    int status;  
  
    // 使用popen執(zhí)行bash命令  
    fp = popen(cmd.c_str(), "r");  
    if (fp == NULL) {  
        perror("popen failed:");  
        return;  
    }
  
    // 讀取命令輸出（可選）  
    char buffer[1024];  
    while (fgets(buffer, sizeof(buffer), fp) != NULL) {  
        cout << buffer;
    }
    //cout << endl;
  
    // 使用pclose關(guān)閉進(jìn)程并獲取返回值  
    status = pclose(fp);  
    if (WIFEXITED(status)) {  
        //int exit_status = WEXITSTATUS(status);  
        //cout << "Command exited with status " << exit_status << endl;  
    } else if (WIFSIGNALED(status)) {  
        int signal_number = WTERMSIG(status);  
        cout << "Command was killed by signal " << signal_number << endl;  
    }
}

void printf_type_info(const string variable, const string typeinfo) {
    cout << variable << ":\t";
    string cmd{"c++filt --type "};
    cmd.append(typeinfo);
    exec_my_cmd(cmd);
}

using std::is_array;

void test_is_array() {
    is_array<int[]> i_no_size;
    is_array<int[16]> is_size_16;
    is_array<int> is_not_size;

    is_array<int[]>::value_type i_no_size_value = is_array<int[]>::value;
    is_array<int[16]>::value_type is_size_16_value = is_array<int[16]>::value;
    is_array<int>::value_type is_not_size_value = is_array<int>::value;
    
    cout << "i_no_size_value:" << i_no_size_value << endl;
    cout << "is_size_16_value:" << is_size_16_value << endl;
    cout << "is_not_size_value:" << is_not_size_value << endl;
    
    printf_type_info("i_no_size", typeid(i_no_size).name());
    printf_type_info("is_size_16", typeid(is_size_16).name());
    printf_type_info("is_not_size", typeid(is_not_size).name());

    printf_type_info("i_no_size_value", typeid(i_no_size_value).name());
    printf_type_info("is_size_16_value", typeid(is_size_16_value).name());
    printf_type_info("is_not_size_value", typeid(is_not_size_value).name());

    int del_int;
    int del_int_array[]{1,2,3};
    int del_int_array_32[32];
    decltype(del_int) del_int_variable;
    decltype(del_int_array) del_int_array_variable;
    decltype(del_int_array_32) del_int_array_32_variable;

    is_array<decltype(del_int)> del_int_is_array;
    is_array<decltype(del_int_array)> del_int_array_is_array;
    is_array<decltype(del_int_array_32)> del_int_array_32_is_array;

    printf_type_info("del_int_is_array", typeid(del_int_is_array).name());
    printf_type_info("del_int_array_is_array", typeid(del_int_array_is_array).name());
    printf_type_info("del_int_array_32_is_array", typeid(del_int_array_32_is_array).name());
}


int main() {
    test_is_array();

    return 0;
}

輸出

[is_array]$ ./test
i_no_size_value:1
is_size_16_value:1
is_not_size_value:0
i_no_size:      std::is_array<int []>
is_size_16:     std::is_array<int [16]>
is_not_size:    std::is_array<int>
i_no_size_value:        bool
is_size_16_value:       bool
is_not_size_value:      bool
del_int_is_array:       std::is_array<int>
del_int_array_is_array: std::is_array<int [3]>
del_int_array_32_is_array:      std::is_array<int [32]>