Cast aways const

[Daok]

Problem :

void Menu::DrawMenu(string sCaption)
{
    char * cTempo = sCaption.c_str();
                 //         int,  int, char*, WORD
    VideoXY(x,0, cTempo ,YELLOW | BLIGHTBLUE);
}//End DrawMenu 

I want to put the string (sCaption )to replace the char*(cTempo)

BUT I got that message :

error C2440: 'initializing' : cannot convert from 'const char *' to 'char *'
        Conversion loses qualifiers

How can I transform the string to char* ???

[Daok]

Here is what I have thought but it doesn't work.

to but a String to a char*

myString.c_str()

But I have that error now : Cannot convert parameter 3 from 'const char *' to 'char *' Conversion loses qualifiers

Anyone can help me?

[abdul]

Try something like this:

char * cTempo = (char8)sCaption.c_str(); 

[parksie]

No need, the function should accept a const char*:

void Menu::DrawMenu(string sCaption) {
                 //         int,  int, char*, WORD
    VideoXY(x, 0, sCaption.c_str(), YELLOW | BLIGHTBLUE);
}//End DrawMenu

Actually, I would suggest using const string &sCaption for performance (saves copying the string when you pass it in, and it lets the compiler inline better in some situations).

[Daok]

VideoXY(x, 0, sCaption.c_str(), YELLOW | BLIGHTBLUE);

doesnt work! I have a constant problem

[parksie]

Where is the VideoXY function declared? Is it one of yours? If so, add the 'const' to the prototype if it doesn't change the source string.

You should *always* put const on something if it doesn't need to change it, to allow it to be used in a greater number of circumstances.

[Daok]

Here is a screenshot that may help us :

[parksie]

Where does the initial function come from? Did you write it or is it API?

[Daok]

I write it but you neeed the LPSTR at the end for the API that call SetPosXYandColor.

DrawMenu use : VIDEOXY who use : SetPosXYandColor who use API

*APi need LPSTR

Daok

[parksie]

Which API function are you using?

[Daok]

Originally posted by abdul
Try something like this:

char * cTempo = (char8)sCaption.c_str(); 

well now it work with something like that :

void Menu::DrawMenu(string sCaption) {
                 //         int,  int, char*, WORD
    VideoXY(x, 0,(char*) (sCaption.c_str()), YELLOW | BLIGHTBLUE);
}//End DrawMenu 

[abdul]

Originally posted by MasterDaok



well now it work with something like that :

void Menu::DrawMenu(string sCaption) {
                 //         int,  int, char*, WORD
    VideoXY(x, 0,(char*) (sCaption.c_str()), YELLOW | BLIGHTBLUE);
}//End DrawMenu 

Ops, ya that "8" should really be "*".

[parksie]

Nooooo.....evil evil evil! Pass by reference!

Then use const_cast<>

[Daok]

const_cast<> will do the same thing?

[parksie]

For example:

void bad_code(char *str) {
    char b;
    while(*str++) {
        b = *str;
    }
}

void my_code() {
    const char *c = "Hello there!";
    // bad_code(c); // won't compile
    bad_code(const_cast<char*>(c));
}

You can mostly get away with it because it's not trying to change it. Nasty things could happen in a ROM environment though :S

[Daok]

Thx it work well that way too