XCode, standard C++ and ifstream file handling.

Question

Recently, I figured out that Xcode could be used to write normal C++ programs.

My problem is with the following code :

#include <iostream>
#include <fstream>
using namespace std;
int main (int argc, char *argv[]) {
    char operation='0';
    int operand=0;
    //open file for reading  
    ifstream ifile;
    ifile.open (argv[1]);
    if(!ifile.is_open()){
            cout<<"Invalid file\n";
            exit(1);
    }
    while(ifile.good())
    {
            ifile>>operation;

            if(operation=='I') {  
                    ifile>>operand;
                    cout<<"Inserting :"<<operand<<endl;
                                                    }
            else
            if(operation=='D') { cout<<"Deleting  "<<endl;
                                                    }
    }
    return 0;
}

When the input is the following ,

I 4
I 8
I 10
I 9
*

When I compile and run in Xcode , I get the following

Loading program into debugger…
Program loaded.
run
[Switching to process 58116]
Inserting :0
Running…

Debugger stopped.
Program exited with status value:0.

I have set the filename as an argument in the project preferences.

However, in the Terminal , I get

Inserting :4
Inserting :8
Inserting :10
Inserting :9

Please help me understand why this happens.

Answer 1

You probably need to specify an absolute path in your project preferences argument.

Answer 2

First as a standard rule when debugging. Eliminate all unnecessary complexity

I suspect your problem is that you are not correctly specifying argv[1] in your debugging parameters, but I could be wrong.

First, try manually specifying the filename rather than accepting it from argv[1]. (The relative path should be from your 'project/build/Debug' directory)

You need to check ifile.good() after you attempt to read the byte, only then would you know if EOF was hit while reading.

Lastly, always check argc when reading argv[].

Answer 3

Use "Edit Active Executable" to access the settings for working directory and command-line arguments.

XCode unfortunately has a few redundant project settings, and you need to open the right window.