Trouble with strings

This is a discussion on Trouble with strings within the C++ Programming forums, part of the General Programming Boards category; Below there's a function that given a string of the form "../data/afile.txt" separates the path("../data/") from the file name("afile.txt"). I ...

  1. #1
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    Jul 2010
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    Trouble with strings

    Below there's a function that given a string of the form "../data/afile.txt" separates the path("../data/") from the file name("afile.txt"). I can get the path succesfully, but unfortunately I can't get the file name correctly.

    Code:
    void SplitStringToFileAndPath(char **file, char **path, const char *string)
    {
        int len = strlen(string);
        int index = 0, j = 0;
    
        // search the string from the end to beggining to find the last '/' or '\' character
        for(int i = len; string[i] != '/' && string[i] != '\\'; i--)
            j++;
    
        // find the position from the beginning of the last '/' or '\'
        index = len - j + 1;
    
        // extract path
        //delete *path;
        *path = new char[index + 1];
    
        // copy path
        for(int i = 0; i < index; i++)
            (*path)[i] = string[i];
    
        (*path)[index] = '\0';
    
        // extract filename
        //delete *file;
        *file = new char[len - index + 1];
    
        for(int i = 0; i < (len - index); i++)
            (*file)[i] = string[(len - index) + i];
    
        (*file)[len - index] = '\0';
    }

  2. #2
    and the hat of wrongness Salem's Avatar
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    Do you have a particular reason for mucking about with allocating char arrays, as opposed to say passing a reference to a std::string to store your results?

    You should simplify the maths
    One copy is
    for ( i = 0, j = 0; j < index ; i++, j++ )

    The other is
    for ( i = 0, j = index+1 ; j < len ; i++, j++ )
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  3. #3
    C++まいる!Cをこわせ! Elysia's Avatar
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    Why something so big complicated and replying on C strings and pointers? Here is simply how I would would do it:
    Code:
    #ifndef GET_PATH_20100802_1812
    #define GET_PATH_20100802_1812
    
    #include <string>
    
    namespace Stuff
    {
    	namespace File
    	{
    		std::wstring GetFile(const std::wstring& strFullPath)
    		{
    			auto pos = strFullPath.rfind(L'\\');
    			if (pos == std::wstring::npos)
    				return L"";
    			return strFullPath.substr(pos + 1);
    		}
    
    		std::wstring GetPath(const std::wstring& strFullPath)
    		{
    			auto pos = strFullPath.rfind(L'\\');
    			if (pos == std::wstring::npos)
    				return L"";
    			return strFullPath.substr(0, pos);
    		}
    	}
    }
    
    #endif
    Combine those two and you have what you want.
    Last edited by Elysia; 02-27-2011 at 06:55 AM.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  4. #4
    Registered User
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    27
    Thanks for help, I corrected the function.

    I use C strings just for training.

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