Question

I’m using linux.

I have a function called like:

PlayBackgroundIntroMusic((char *)"IntroMusic");

The functions is:

void SoundManager::
PlayBackgroundIntroMusic( char * musicFile)
{
        // Concatenate extension for each platform
        strcat (musicFile,audioExtension);
        CCLOG("musicFile: %c" musicFile);
  SimpleAudioEngine::sharedEngine()->playBackgroundMusic(std::string(CCFileUtils::fullPathFromRelativePath(musicFile)).c_str(), false);
}

But i having a bad access to memory on line:

strcat (musicFile,audioExtension);

audioExtension is declarated:

#include 
using std::string;
#include 
using std::cout; using std::cerr; using std::endl;

/**
 * Declare sound extension for each platform
 * Android = ogg
 * iOS = caf
 * WIN32 = mp3
 */

#if (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32)
        static const char * audioExtension = ".wav";
#elif (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
        static const char * audioExtension = ".caf";
#elif (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)
        static const char * audioExtension = ".ogg";
#endif

So, i expected to have:

IntroMusic.caf on iOS
IntroMusic.ogg on Android

What’s is happening?

NOTE: I have tried to:

 char * musicFileWithExtension = strcat (musicFile,audioExtension);

But it didn’t work anyway.

musicFile is not a constant. I don’t want to declarate a tempchar[80] to avoid overflow if the name of the file is too long like Example cc reference

Thanks in advance.

Answer 1

String literals, such as "IntroMusic" are of type const char[N] which is implicitly convertible to const char *. Through a mistake in language design, it is also convertible to char*, but that conversion is rightfully deprecated in C++, hence the warning. You need to use an array (dynamically or statically allocated), not a string literal.

Or better yet, use std::string.