CODEWITHSUNDEEP
c++c++11constructornamespaces
Adi
Adi

Reputation: 13

Getting an error for initalisation of the constructor

This is my process.cpp

#include<iostream>
  #include "process.h"
  #include "CString.h"
   void process(const char* s){
    w1::Cstring cs(s);
    std::cout << cs;
   }

My CString.h

#ifndef _CSTRING_H
#define _CSTRING_H
#include<iostream>
namespace w1{
const int CHAR_NUM=3;
class Cstring{
public:
    char str[CHAR_NUM+1];
    Cstring(char* s);
    void display(std::ostream& os) const;

};
std::ostream& operator<<(std::ostream&os ,const Cstring& cs);
}
#endif

And this is my CString.cpp

#include <iostream>
#include "CString.h"
namespace w1{
Cstring::Cstring(char* s){
    if (s=='\0'){
        str[0]='\0';
    }else{
        for (int i=0;i<CHAR_NUM;i++){
            str[i]=s[i];
            str[i+1]='\0';
        }
    }
}
void Cstring::display(std::ostream& os) const{
    os<<str<<std::endl;
}

std::ostream& operator<<(std::ostream&os ,const Cstring& cs){
    cs.display(os);
    return os;
}
}

I am getting an error which says that I dont have any matching constructor for initialisation of w1::CString in process.cpp I dont know how to correct it.

Upvotes: 0

Views: 52

Answers (2)

owacoder
owacoder

Reputation: 4873

I would recommend changing the parameter type of the constructor to const char * instead, if the constructor does not modify the parameter, as in your code. Compilers are allowed to implicitly convert non-const to const, but not the other way around, as your code shows.

Upvotes: 1

TheUndeadFish
TheUndeadFish

Reputation: 8171

You wrote your constructor Cstring(char* s); as taking a non-const pointer. But your function void process(const char* s) is trying to pass it a const pointer. The compiler won't automatically cast away constness (and for good reason).

However since that constructor doesn't seem to be modifying its parameter, you should change it to a const pointer:

Cstring(const char* s);

And thus that error will be solved.

Upvotes: 4

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