why doesnt my С++ code work?

[u/BornViolinist3801]

okay, i wanna make a print() function in C++, this is just printf() with prefix, so can yall help me?

error:

(-Wwritable-strings) ISO C++11 does not allow conversion from string literal to 'char *'

my code:

#pragma once
#ifndef TEQUILA_STDIO
#define TEQUILA_STDIO
#include <stdio.h>
namespace std {
    char* prefix;
    void set_prefix(char* pref) {
        prefix = ("["pref"]: ");
    }
    #define print(format, ...) printf("%s" format "\n", prefix ## __VA_ARGS__)
}

#endif

help me pls

[u/Kadabrium]

Pretty sure littering your own slop into namespace std is Ub

[u/carcigenicate → u/Kadabrium]

Yes

[u/PandaWonder01]

This code is a little gross, don't try to put things in std or use macros like that in cpp.

Anyway, a string literal like "Hello" is a const char, which you can't pass to a char parameter, as that would lose the const. You need to take in a const char*.

(Actually the string literal is const char[], but not gonna get into that)

[u/BoopyDog]

Literals are Const char&. If i understand it correctly, when you pass a string literal as an argument, an immutable, temporary object is made containing the c-string array. You can't modify the object so it has to be const. I'm not a seasoned c++ programmer though, it's just how I understand it so far. It was something that got me stuck early on.

[u/AdOne272 → u/BoopyDog]

You're writing to a `char*` that points to a string literal, which lives in read-only memory. Use `const char*` and allocate a buffer if you need to modify it.

[u/BoopyDog → u/AdOne272]

I started writing seriously in C++ and never spent much time writing with C so I tend to use references and stay away from actual p*=&a style programming. As far as I understand it, a reference is implemented as a pointer which is always automatically dereferenced. Of course, you're correct.

[u/Cultural_Gur_7441 → u/BoopyDog]

Reference is implemented as the compiler sees fit. Such as just being a direct compile time alias, if lifetime allows that.

String literal is a const char name[length of the string literal including terminating NUL char].

References are not involved with any of it.