Reading input from a file with getline

Question

I seem to have a fundamental misunderstanding on file input. I assumed my method would work for a project I am working on, but it simply does not. Here is the code:

#include <iostream>

#include <fstream>

#include <cstring>

using namespace std;

int main(){
   ifstream input;
   char fname[20], lname[20];
   input.open("text.txt");

   input.getline(lname, 20, ',');
   input.getline(fname, 20, ' ');
   cout << lname;
   cout << fname;

}

From a file I have:

Squarepants, Spongebob

and the cout statements do not output anything

What I am doing wrong?

thanks

Assuming the file actually gets opened (I mean you've provided no details to that end, so maybe it didn't), and that the reads succeed, there is output. — Qaz
– Qaz, Commented Apr 6, 2015 at 23:32
Make sure your file is opened successfully. Also, always verify that the read operations are successful. — Dietmar Kühl
– Dietmar Kühl, Commented Apr 6, 2015 at 23:32
@user3470987, You told it to read up to the next space. It's at the beginning. — Qaz
– Qaz, Commented Apr 6, 2015 at 23:59
Either use input.ignore(), or get rid of the third argument in the second call to getline. — David G
– David G, Commented Apr 7, 2015 at 2:13

mrflash818 · Accepted Answer · 2015-04-07 02:02:03Z

1

This might be a good pattern to use:

std::string lineOfText;

while(fileAccessor.good()) {
    fileAccessor.getline(lineOfText);
    //
    // do stuff
    // do stuff
    //
    if(fileAccessor.eof()) break;
}

answered Apr 7, 2015 at 2:02

mrflash818

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1 Comment

Remy Lebeau Over a year ago

Or, remove the individual good() and eof() checks and just use while(fileAccessor) instead. Streams have an operator bool() that returns false when the stream is in bad, fail or eof state.

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