Strings and Chars

This is a discussion on Strings and Chars within the C++ Programming forums, part of the General Programming Boards category; I want to save some variables to a data text file, problem is the only way to do this i ...

  1. #1
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    Jul 2002
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    17

    Strings and Chars

    I want to save some variables to a data text file, problem is the only way to do this i know of uses a "char *", I need to save some "String" type variables into the txt file that can be reloaded properly, I have tried.

    Code:
    String Test = "hello";
    
    char * Test2 = Test.c_str();
    but that doesn't load or save properly, I'm using Borland Visual Compiler, can anyone write me an example if it is possible?

  2. #2
    Shadow12345
    Guest
    Umm I would just try doing
    char * NameOfSomething = "Cheese"

    That's the way I would do it, and it should work

  3. #3
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    I don't wanna preset the variable like that, I have an external const char * with names within it that I want to use to set the other type of variables to begin with. But I seem to have to use a String else I get "|||[][]|" type of junk come up instead of the actual text, so I need to learn to find a way to safely output the String type variable/object to a text file and be able to reload it later..
    Scorpion-ice
    Imperium et Respectus

  4. #4
    Registered User
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    Here is one solution.

    Code:
    // _TEXT is a macro in tchar.h for support of UNICODE
    string sText = _TEXT("September 28, 2002");
    size_t textSize = sText.size();
    
    // Allocate one addition byte for NULL. 
    TCHAR *pText = new TCHAR[textSize + 1];
    
    // _tcscpy() is defined in tchar.h.
    // It is similar to strcpy() except it supports UNICODE.
    _tcscpy(pText, sText.c_str());
    
    pText[textSize] = NULL;
    ...
    
    delete [] pText;
    Kuphryn

  5. #5
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    any idea how you would be able to save the String to a text file and be able to load it back up without any problems?
    Scorpion-ice
    Imperium et Respectus

  6. #6
    Code Goddess Prelude's Avatar
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    >any idea how you would be able to save the String to a text file and be able to load it back up without any problems?
    An std::string is simply a list of characters, if you use just about any output routine to write to the text file then it should work:

    fout<<Test;

    If it doesn't then maybe the problem is not in how you read and write or in the data type:
    Code:
    #include <iostream>
    #include <fstream>
    #include <string>
    #include <cstdlib>
    
    int main()
    {
      // Write a string to file
      std::ofstream out ( "info.txt" );
    
      if ( !out.is_open() ) {
        std::cerr<<"Error opening file for writing"<<std::endl;
        exit ( EXIT_FAILURE );
      }
    
      std::string test = "This is a test";
      out<<test;
      out.close();
    
      // Read the string back
      std::ifstream in ( "info.txt" );
    
      if ( !in.is_open() ) {
        std::cerr<<"Error opening file for reading"<<std::endl;
        exit ( EXIT_FAILURE );
      }
    
      std::string input;
      std::getline ( in, input );
      std::cout<<"The string we saved is: "<< input <<std::endl;
    
      // Start over, but read into an array
      in.seekg ( 0, std::ios::beg );
      char a_input[15];
      in.getline ( a_input, 15 );
      std::cout<<"The string we saved is: "<< input <<std::endl;
    
      return EXIT_SUCCESS;
    }
    -Prelude
    My best code is written with the delete key.

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