Opening Text File

This is a discussion on Opening Text File within the C++ Programming forums, part of the General Programming Boards category; I am reading a text file which has two columns of data. The following program works when readfile.open(afile) is replaced ...

  1. #1
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    Opening Text File

    I am reading a text file which has two columns of data. The following program works when readfile.open(afile) is replaced simply with readfile.open("001.txt"). Why does it not work when I declare afile beforehand? Although it may not seem important for this particular code, it is necessary for my future tasks. Thank you in advance.

    Code:
    #include <iostream>
    #include <fstream>
    using namespace std;
    
    int main (){
    	string afile = "001.txt";
        	ifstream readfile;
        	readfile.open(afile);
    	const int n = 10;
        	double x[n], y[n];
        	for (int i=0; i<n; i++)
    	{
    		readfile>>x[i]>>y[i];
    		cout<<x[i]<<" "<<y[i]<<endl;
    	}
    
    	
    	readfile.close();
    }

  2. #2
    spurious conceit MK27's Avatar
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    First parameter to open is a C-string, not a std::string. Try:

    Code:
    readfile.open(afile.c_str());
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  3. #3
    and the hat of wrongness Salem's Avatar
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    You need to say this

    Code:
    readfile.open(afile.c_str());
    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.
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  4. #4
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    Thanks a lot. Works perfectly.

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