Thread: Never seen an error like this before

I'm relatively new to programming, and when I first compiled this program I got a whole slue of errors and slowly whittled it down to the last outstanding error which was for line 93, I had

Code:

fin.open(file_name)

and fixed it by making it

Code:

fin.open("file_name")

but when I tried to compile it after that I got an error that I can't make any sense of. the error reads:

Code:

/usr/local/gcc/lib/gcc/sparc-sun-solaris2.10/4.5.2/crt1.o: In function `.nope':
/usr/local/src/gnu/gcc/gcc-4.5.2/gcc/config/sparc/sol2-c1.asm:94: undefined reference to `main'
collect2: ld returned 1 exit status

I don't have a function '.nope' and i'm not sure what the undefined reference to the main 'main' is given that I haven't even crated a main file yet. Can anyone help me out with this?

Code:

#include <iostream>#include <cstdlib>
#include <fstream>
#include <string>
#include "MyTime.h"
using namespace std;


MyTime::MyTime(){


  hours = 0;
  minutes = 0;
  simplify();


}


MyTime::MyTime(int& time1, int& time2){


  time1 = hours;
  time2 = minutes;


}


void MyTime::set_time(int time1, int time2){


  hours = 0;
  minutes = 0;
  simplify();


}


int MyTime::get_time1()const{


  return hours;


}


int MyTime::get_time2()const{


  return minutes;


}


istream& operator >> (istream& ins, MyTime t1){


  char selection1, selection2;
  string file_name;
  ifstream fin;
  int num1 = 0, num2 = 0, tmp1 = 0, tmp2 = 0;


  cout << "Do you want to input the number of hours and minutes now or from a file? (enter N for now and F for file): ";
  cin >> selection1;


  while (selection1 != 'n' && selection1 != 'N' &&
      selection1 != 'f' && selection1 != 'F'){
    cout << "Please enter a valid selection.  N or F: ";
    cin >> selection1;
  }


  if (selection1 == 'n' || selection1 == 'N'){
    cout << "Enter the number of hours: ";
    ins >> t1.hours;


    cout << "Enter the number of minutes: ";
    ins >> t1.minutes;
  }


  else if (selection1 == 'f' || selection1 == 'F'){
    cout << "Please enter the name of the file that has the number of minutes and hours: ";
    cin >> file_name;


    fin.open("file_name");
    if (fin.fail()){
      cout << "The file " << file_name << " does not exsist in this folder, please put the file into this folder " << endl
           << " or hole CRTL + C to close out of this program: ";
      cin >> file_name;
    }


    while (fin >> num1 >> num2){
      tmp1 += num1;
      tmp2 += num2;
    }


    cout << "Your file has a total of " << tmp1 << " hours and " << tmp2 << " minutes.  If this is backwards and the totals " << endl
         << "should be " << tmp2 << " hours and " << tmp1 << " minutes and you would like the correct this please type Y, and if you "<< endl
         << "do not wish to correct this type N: ";
    cin >> selection2;


    while (selection2 != 'y' && selection2 != 'Y' &&
           selection2 != 'n' && selection2 != 'N')
      cout << "Please enter a valid selection, Y or N: ";
      cin >> selection2;


    if (selection2 == 'n' || selection2 == 'N'){
      t1.hours = tmp1;
      t1.minutes = tmp2;
      ins >> t1.hours >> t1.minutes;
    }


    else if (selection2 == 'y' || selection2 == 'Y'){
      t1.hours = tmp2;
      t1.minutes = tmp1;
      ins >> t1.hours >> t1.minutes;
    }
  }




  return ins;


}


void MyTime::simplify(){


  int tmp1, tmp2;


  if (minutes >= 60){
    tmp1 = minutes / 60;
    tmp2 = minutes % 60;
    hours += tmp1;
    minutes += tmp2;
  }


}

Change

Code:

fin.open(file_name);

to

Code:

fin.open(file_name.c_str());

Open accepts a const char* as the first parameter. Your file_name is a std::string object, so you must pass the c-string in to the open function, and this is achieved by the c_str member function.

don't have a function '.nope' and i'm not sure what the undefined reference to the main 'main' is given that I haven't even crated a main file yet. Can anyone help me out with this?

If you don't have a function called main, you can't compile the program. Every C and C++ program needs a main function, no exceptions. The error you are getting is not a compiler error, it is a linker error. This is probably why it looks abit strange to you.

The process of building an executable is a two-step process, compilation of source files into object files which is then followed by a linking step which combines all the compiled object files - plus additional libraries - into a final executable. You can certainly compile a source file into an object file without a main function (main is a function not a program). The issue comes when you try to build the executable and the linker needs to find a main function as the executable's starting point. You may have been trying to build (which would involve the second linking step) instead of just simply attempting to compile.