如何在C ++中比较两个字符串并使用默认函数？

Question

I am working on my first ever c++ code and i am having some diffuclties the strcmp function couldn't be resolved!! Even though i did in h file: using std::string; I am working with Eclipse, so I did an h and cpp files in the h file i have this :

#include <iostream>
#include <string>
#include <set>

using std::set;
using std::string;

namespace AA{
namespace BB{


    typedef enum{
        EASY , MEDIUM, HARD
    } Difficulty;

    class FIRST{
    private:
        char* name;
        Difficulty difficulty;

    public:       
        FIRST(const std::string& name, const Difficulty& difficulty);

        FIRST(const FIRST& first) = default;




    };
} // end of namespace BB
} 

// end of namespace AA

and in the cpp file I did this but i get eror that

Function strcmp could not be resolved 'strcmp' is not a member of 'std'

#include <iostream>
#include <string>
#include <set>
#include "Enigma.h"
#include <stdbool.h>

AA::BB::FIRST(const std::string& name, const Difficulty& difficulty):
    difficulty(difficulty),  name(name) {
}


bool AA::BB::FIRST::operator==(const FIRST& first) const{
    if((difficulty==(FIRST.difficulty))&&(strcmp(name,first.name)==0)){
        return true;
    }
    return false;
}

Answer 1

Why compare with strcmp , when you can make use of the existing == operator:

bool AA::BB::FIRST::operator==(const FIRST& first) const{
    if((difficulty == FIRST.difficulty) && (name == first.name)){
        return true;
    }
    return false;
}

Or you could use its compare function which would yield the same result:

bool AA::BB::FIRST::operator==(const FIRST& first) const{
    if((difficulty == FIRST.difficulty) && (name.compare(first.name) == 0){
        return true;
    }
    return false;
}

Answer 2

When you want to use a certain function you can go to some reference site , find out which header should be included in order to use this function ( <cstring> in this case) and then include it.

You should also figure out the code style you are using. CAPS names are typically only used for macros (because they are evil).

Answer 3

The function strcmp is C. There are no strings as you know them from C++. See here: http://www.cplusplus.com/reference/cstring/strcmp/

You could do:

#include <string>

int main()
{
    std::string name = "Webber";
    std::string firstName = "John";

    if (strcmp(name.c_str(), firstName.c_str()) == 0)
        ...
}

This will copy your C++ String to an char-Array