使用strcat对内存的访问错误

问题描述

我正在使用linux.

I'm using linux.

我有一个像这样的函数

PlayBackgroundIntroMusic((char *)"IntroMusic");

功能是:

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);
}

但是我无法在线访问内存:

But i having a bad access to memory on line:

strcat (musicFile,audioExtension);

audioExtension被声明:

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

所以，我希望有:

IntroMusic.caf on iOS
IntroMusic.ogg on Android

发生了什么事?

注意:我已经尝试过:

 char * musicFileWithExtension = strcat (musicFile,audioExtension);

但是它还是没有用.

musicFile不是常数.如果文件名太长，例如抄送参考示例

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

谢谢.

推荐答案

字符串文字，例如"IntroMusic" 的类型为 const char [N] 可转换为 const char * .由于语言设计中的错误，它也可以转换为 char * ，但是该转换在C ++中已被正确弃用，因此发出警告.您需要使用动态分配或静态分配的数组，而不是字符串文字.

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.

或更妙的是，使用 std :: string .

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