Demonstrate changing the directory to the executable's path using C++

file.txt

This is a one.
This is line two.
This is line three.

setcwd.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <unistd.h>

using namespace std;

int main(int argc, const char **argv)
{
    string exename = argv[0];
    string path = exename.substr(0, exename.find_last_of("/"));
    cout << "Changing to directory '" << path << "'" << endl; 
    chdir(path.c_str());

    ifstream file("file.txt");
    string line;
    while (getline(file, line))
        cout << line << endl;	
	
    return 0;
}

Test results

--- Source/cpptinkering ‹master*➔ ?› » make
clang++ -DDEBUG=1 -g -Wall -std=c++11 -stdlib=libc++ -o setcwd setcwd.cpp  -lstdc++
--- Source/cpptinkering ‹master*➔ ?› » ./setcwd
Changing to directory '.'
This is a one.
This is line two.
This is line three.
--- Source/cpptinkering ‹master*➔ ?› » cd /
--- / » /Users/andy/Source/cpptinkering/setcwd
Changing to directory '/Users/andy/Source/cpptinkering'
This is a one.
This is line two.
This is line three.