Include C++ File to another C++ File

Question

I'm havin a problem in including my files. I got 3 C++ files and all of them got int main(void).

THe problem is whenever i include 1 of them it says that:

function 'int main(void)' already has a body

but if i will remove the int main(void) to other two C++ file this errors will prompt now.

'one or more multiply defined symbols found'

"class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl convertInt(int)" (?convertInt@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z) already defined in FormatPosDataXml().obj

"class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl convertInt(int)" (?convertInt@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z) already defined in FormatPosDataXml().obj    

and so forth

this is the codes that i've got:

FormatPosDataXml().cpp

#include <iostream>
#include <sstream>
#include <vector>
#include <string>
#include <cstring>
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>



using namespace std;

#define nextline '\n'

inline bool TextContains(char *text, char ch) {
  while ( *text ) {
    if ( *text++ == ch )
      return true;
  }

  return false;
}

void Split(char *text, char *delims, vector<string> &words) {
  int beg;
  for (int i = 0; text[i]; ++i) {

    while ( text[i] && TextContains(delims, text[i]) )
      ++i;

    beg = i;

    while ( text[i] && !TextContains(delims, text[i]) )
      ++i;
        words.push_back( string(&text[beg], &text[i]) );
  }
}

string convertInt(int number)
{
   stringstream ss;//create a stringstream
   ss << number;//add number to the stream
   return ss.str();//return a string with the contents of the stream
}


string dateFormatChecker(const char *date){
    string strdate=date;
    char getdate[50];
    strcpy_s(getdate, strdate.c_str());

    vector<string> checkdate;
    Split( getdate, "-", checkdate );
    int year, month, day;
    year=atoi(checkdate[0].c_str());
    month=atoi(checkdate[1].c_str());
    day=atoi(checkdate[2].c_str());

    string checkyear, checkmonth, checkday, checkhour, checkminute, checksecond;

            checkyear = convertInt(year);
            if(month<10){
            checkmonth = "0" + convertInt(month);
            }
            else{
            checkmonth = convertInt(month);
            }
            if(day<10){
            checkday = "0" + convertInt(day);
            }
            else{
            checkday = convertInt(day);
            }

            /*
            cout << checkdate[0] << ' ' << checkyear << '\n'
                 << checkdate[1] << ' ' << checkmonth << '\n'
                 << checkdate[2] << ' ' << checkday << '\n';
            */
            if (checkyear.size() != checkdate[0].size()||
                checkmonth.size() != checkdate[1].size()||
                checkday.size() != checkdate[2].size()){
                return "";
            }
    return date;
}

string dateandtimeFormatChecker(const char *dateandtime){
        string strdate=dateandtime;
        char getdateandtime[50];
        strcpy_s(getdateandtime, strdate.c_str());

        vector<string> checkdateandtime;
            Split( getdateandtime, "-: ", checkdateandtime );
        int year, month, day, hour, minute, second;
            year=atoi(checkdateandtime[0].c_str());
            month=atoi(checkdateandtime[1].c_str());
            day=atoi(checkdateandtime[2].c_str());
            hour=atoi(checkdateandtime[3].c_str());
            minute=atoi(checkdateandtime[4].c_str());
            second=atoi(checkdateandtime[5].c_str());

            string checkyear, checkmonth, checkday, checkhour, checkminute, checksecond;

            checkyear = convertInt(year);
            if(month<10){
            checkmonth = "0" + convertInt(month);
            }
            else{
            checkmonth = convertInt(month);
            }
            if(day<10){
            checkday = "0" + convertInt(day);
            }
            else{
            checkday = convertInt(day);
            }
            if(hour<10){
            checkhour = "0" + convertInt(hour);
            }
            else{
            checkhour = convertInt(hour);
            }
            if(minute<10){
            checkminute = "0" + convertInt(minute);
            }
            else{
            checkminute = convertInt(minute);
            }
            if(second<10){
            checksecond = "0" + convertInt(second);
            }
            else{
            checksecond = convertInt(second);
            }


            if (checkyear.size() != checkdateandtime[0].size()||
                checkmonth.size() != checkdateandtime[1].size()||
                checkday.size() != checkdateandtime[2].size()||
                checkhour.size() != checkdateandtime[3].size()||
                checkminute.size() != checkdateandtime[4].size()||
                checksecond.size() != checkdateandtime[5].size()){
                return "";
            }

        //cout << year<< '/' << month << '/' << day << ' ' << hour << ':' << minute << ':' << second << '\n';

        return dateandtime;     
}

string transaction (const char * SequenceNumber, const char * RetailStoreID, const char * WorkStationID, const char * BusinessDayDate, const char * BeginDateTime, const char * StartTransTime, const char * EndTransTime, const char * EndDateTime, const char * RawData){

    string output;

    string bdd, bdt, stt, ett, edt;

    bdd = dateFormatChecker(BusinessDayDate);
    bdt = dateandtimeFormatChecker(BeginDateTime);
    stt = dateandtimeFormatChecker(StartTransTime);
    ett = dateandtimeFormatChecker(EndTransTime);
    edt = dateandtimeFormatChecker(EndDateTime);


    cout << "<Transaction>" << "\n\t<RetailStoreID>"
         << RetailStoreID   << "</RetailStoreID>\n\t<WorkStationID>"
         << WorkStationID   << "</WorkStationID>\n\t<SequenceNumber>"
         << SequenceNumber  << "</SequenceNumber>\n\t<BusinessDayDate>"
         << bdd             << "</BusinessDayDate>\n\t<BeginDateTime>"
         << bdt             << "</BeginDateTime>\n\t<StartTransTime>"
         << stt             << "</StartTransTime>\n\t<EndTransTime>"
         << ett             << "</EndTransTime>\n\t<EndDateTime>"
         << edt             << "</EndDateTime>\n\t<RawData>"
         << RawData         << "</RawData>\n</Transaction>";

    output = _getch();
    return output; 
}

int main(void) {
  vector<string> words;
  char * data = "1,1,SAMPLE,2010-01-31,2011-01-31 14:09:10,2011-01-31 14:42:10,2011-01-31 14:42:10,2011-01-31 14:42:10,JELLY-O RUBBERB\n\r               13.25V.¶üÁËO";

  Split( data, ",", words );

  char SN[11], RSI[200], WSI[200], BDD[100], BDT[100], STT[100], ETT[100], EDT[100], RD[100];

  strcpy_s(SN, words[0].c_str());
  strcpy_s(RSI, words[1].c_str());
  strcpy_s(WSI, words[2].c_str()); 
  strcpy_s(BDD, words[3].c_str());
  strcpy_s(BDT, words[4].c_str());
  strcpy_s(STT, words[5].c_str());
  strcpy_s(ETT, words[6].c_str());
  strcpy_s(EDT, words[7].c_str());
  strcpy_s(RD, words[8].c_str());

  string PosData;
  PosData = transaction(SN,RSI,WSI,BDD,BDT,STT,ETT,EDT,RD);


/* Checker 
  for (int i = 0; i != words.size(); i++){
      cout << words[i] << nextline;
  }
    cout << SN << nextline << RSI << nextline << WSI << nextline << BDD << nextline << BDT << nextline << STT << nextline << ETT << nextline << EDT << nextline << RD; 
*/
return 0;
}

FSNPC.cpp

#include <iostream>
#include <sstream>
#include <vector>
#include <string>
#include <cstring>
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include "FormatPosDataXml().cpp"

using namespace std;


string getstring(string holder){
    if (holder == "" || holder.size()>100){
        exit(1);
    }

    int i=0,ch=0;
    int size;
    char charInput[100];

        strcpy_s(charInput, holder.c_str());
        size = strlen(charInput);

        #define DATA_LENGTH 100
        #define BUFFER_LENGTH (DATA_LENGTH)

        char Buffer[BUFFER_LENGTH];

            while (i < DATA_LENGTH) {
                Buffer[i++] = charInput[i];
                Buffer[i] = '\0';
                if(size == i){
                        break;
                    }
            }
            holder = Buffer;

            strcpy_s(charInput, holder.c_str());
            size = strlen(charInput);

            i = 0;
            for(int j = 0;j<size;j++)
            {
                if (charInput[j] < 2) 
                {
                    if (charInput[j+i] > 2 && charInput[j+i] != 17){
                        charInput[j] = charInput[j+i];
                        charInput[j+i]='\0';
                        i=0;
                        }
                    else{
                        i++;
                        j--;
                    }
                }else if (charInput[j] == 17) 
                {
                    if (charInput[j+i] > 2 && charInput[j+i] != 17){
                        charInput[j] = charInput[j+i];
                        charInput[j+i]='\0';
                        i=0;
                        }
                    else{
                        i++;
                        j--;
                    }
                }
            }
            size = strlen(charInput);
            for(int remove = 0; remove<size ;remove++)
            {
                if (charInput[remove] < 2 || charInput[remove] == 17) 
                {
                    charInput[remove]='\0';
                }
            }

             string handler;
             handler = charInput;

             handler = handler.substr(0, handler.length() - 1);
             return (handler);
    }



/*
int main(void){

    string final;


    string input = "JELLY-O RUBBERB\n\r               13.25V.¶üÁË0";
    string input2 = "STIÁËCK-O CHOCO\n\r               10.52C.ÁË0¶ü";
    string input3 = "STICÁËK-O VANILLA\n\r               10.52C.ÁË0¶ü";


      final = getstring(input)+ "\n" +getstring(input2)+ "\n"
+getstring(input3);
        cout<<final;
        _getch();


    return 0;

}*/

keypress.cpp

#include <iostream>
#include <conio.h>
#include <stdio.h>
#include <string>
#include "FormatPosDataXml().cpp"

    using namespace std;

int c;
char temp[256];

    char getkeypress(char c){

        if (c==0x1b){
            exit(1);
         }

         else if (c==0||c==224)        
          {
                    c = _getch();

                    if (c==0x3b){
                        cout << "You typed: F1\n";
                    }
                    else if(c==0x3c){

                        cout << "You typed: F2\n";
                    }
                    else if(c==0x3d){
                        cout << "You typed: F3\n";
                    }
                    else if(c==0x3e){
                        cout << "You typed: F4\n";
                    }
                    else if(c==0x3f){
                        cout << "You typed: F5\n";
                    }
                    else if(c==0x40){
                        cout << "You typed: F6\n";
                    }
                    else if(c==0x41){
                        cout << "You typed: F7\n";
                    }
                    else if(c==0x42){
                        cout << "You typed: F8\n";
                    }
                    else if(c==0x43){
                        cout << "You typed: F9\n";
                    }
                    else if(c==0x44){
                        cout << "You typed: F10\n";
                    }
                    else if(c==133){
                        cout << "You typed: F11\n";
                    }
                    else if(c==134){
                        cout << "You typed: F12\n";
                    }
          }

          else
          { 
                while((cin.getline(temp, sizeof(temp), '\n'))&&(temp!="")){
                    cout << "You typed:" << temp << '\n';
                    break;
                }
          }

    }
/*  
int main(void){



    while (c^=0x1b){
            cout<<"Press any key:\n";
            c = getkeypress(_getch());
    } 
      _getch();
      return 0;
}
*/

how could I link all of these files. I want them to be a library. How could i do it then?

Answer 1

In general, it is bad practice to include another .cpp file inside of a .cpp file. The right way is to break out declarations into .h files and put the definitions in .cpp files. Make sure to put a bogus define at the top of each of your .h files to prevent accidental re-inclusion, as in:

#ifndef MYFILE_H_
#define MYFILE_H_

// your code goes here

#endif

When you compile your program, you need to compile all the .cpp files into .o files (or .obj on Windows), and then link them together. For example (Linux/Mac):

g++ -c foo.cpp
g++ -c bar.cpp
g++ foo.o bar.o -o theMainExecutable

Answer 2

You can't include .cpp files, you need to use .h files, which are definitions for functions. Define the stuff in the header files, then implement them (Write the code for them) in the .cpp files.

int main() can only go in one .cpp file, you need to put your code in a function, define it in a header, then include into your main file, then execute it in int main().

Answer 3

I haven't read all the code, but I would guess you are defining the same function in two modules. Firstly, you should not have a main in all three files. Only one of them. If you are planning to make a library, none of the files should have a main -- that should be in the program which imports your library.

As for convertInt, I suspect it is defined in multiple files. If it isn't, then perhaps it is defined in a header file. You should only put declarations in a header file, such as this:

string convertInt(int number);

(note the semicolon)

The definition should always appear in the corresponding CPP file, like this:

string convertInt(int number) { ... // Body of the function }

If the definition appears in the header file, you have a problem, because every CPP file which #includes that header will contain a duplicate definition.

Answer 4

Without weeding through your huge jumble of code, it seems that you are trying to merge different source files into the same project resulting in conflicting names.

I think you will just need to find a way to structure your code so that you don't get conflicting symbols. You obviously cannot have three different entry-points in your application. Which one do you want to be called? If you want the user to choose, for example, then you have to write the code for this, and name your functions accordingly.

For example with convertInt, if you need to include different variations of this function in your application, then you will need to name it properly to distinguish it.

Possible solutions for convertInt include:

1. Wrap convertInt (and possibly other functions) in a namespace, and call them like Variation1::convertInt(x)
2. Just give things unique names. convertInt1, convertInt2, etc.
3. Take the time to merge related functions. I doubt that two functions named convertInt, in the same project, with the same signature, actually do different things. Merge them so there is only 1 function to think about.

Apologies if my answer has nothing to do with your problem.

Answer 5

The Technique I use as to import classes and variables from other files is : (as I know of)

• Importing the Raw C++ File(s). [Tho not the most preferred method.]

Let's say I've two C++ Files :

file_1.cpp

#include<iostream>
using namespace std;

int x = 8;            // A Random Variable

class Math{           // A Random Class

    public:

        static int multiplyBy5(int x){
            return x * 5;
};

file_2.cpp [The Driver File let's Say]

#include<iostream>
#include "file_2.cpp"                // This can be the Relative/Absolute Path.
using namespace std;

int main()
{
    // Importing External Variable present in the imported File. [Tho we don't need to define `extern` as we're importing the whole file itself.]
    extern int x;                    
    cout<<x<<endl;
    cout<<Math::multiplyBy5(5)<<endl;
    return 0;
}

Note :

1. The main() method should exist only in the Driver Program. Defining main() method in other files will break your driver code.
2. You can replace the .cpp extensions of the files being imported by .h [Interface] which is considered a better practice then importing directly the raw .cpp.
3. Doing so, you don't need to compile the other files you're importing. So, basically you can access and run all the files all together by simply running the driver code i.e. -

g++ file_2.cpp -o file_2
./file_2