allocation problem

This is a discussion on allocation problem within the C++ Programming forums, part of the General Programming Boards category; I'm rewriting a program I made before because I lost the source and I want to allocate a number of ...

  1. #1
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    allocation problem

    I'm rewriting a program I made before because I lost the
    source and I want to allocate a number of text strings that are 500 characters long.
    So I tried this:
    char *m_IDs[500]=(char *)malloc(m_NumberOfStrings);

    That obviously doesn't work, but I can't remember how to do it.

    Thanks in advance,

    SSJBardock

  2. #2
    Master of the Universe! velius's Avatar
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    Since your using C++ it is prefered to use new.
    Code:
    // allocate an array of pointers to char*
    char** m_IDs = new char*[m_NumberOfStrings];
    // allocate memory for each one
    ...
    m_ID[i] = new char[nLengthOfString];
    ...
    delete [] m_ID[i];
    ...
    delete [] m_ID;
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  3. #3
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    Thanks, that almost works, but for some reason when I make m_NumberOfStrings higher than 1015 (nLengthOfString being 500) I get an assert error.

    Do you have any idea what's the problem and how to fix it?

  4. #4
    Carnivore ('-'v) Hunter2's Avatar
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    I can't say for sure, but in any case you're trying to allocate half a megabyte in that statement

    But since this is C++ and you're using an array of c-strings, I suggest you try using a std::vector of std::string's. Just a suggestion Generally in C++, vectors are preferred over arrays since they can do pretty much everything arrays can but easier and in many cases better, and strings are preferred over char* for the same reason.

    Code:
    #include <vector>
    
    std::vector<std::string> m_IDs;
    m_IDs.push_back("SomeID");
    m_IDs.push_back("SomeOtherID");
    
    for(int i = 0; i < m_IDs.size(); ++i)
    {
         doSomething(m_IDs[i]);
    }
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