I am beginner at C++ (or all coding in general). That being said, I am trying to understand what return 0/return 1/return -1 defines outside of the main() function.
What I do know about Return values is that it allows one to end a statement and get a "return" integer value. I was told (by my professor) that return 0 is like a "achieved" status. Telling the user that everything is working fine.
However what is confusing me is the code below. Inside "int checkwin()" function it states that if a player wins, then the code will input "return 1". If no one wins, then "return 0". And the last one I don't understand completely (assuming it means keep going) because again, I haven't figured the definitions for return 0/1/-1.
#include <iostream>
using namespace std;
char square[10] {'0','1','2','3','4','5','6','7','8','9'};
int checkwin();
void board();
int main()
{ // main function OPEN
int player;
int i;
int choice;
char mark;
do { // do while loop open
board();
player=(player%2)?1:2;
cout << "Player " << player << ", enter a number: ";
cin >> choice;
mark =(player ==1) ? 'X' : 'O';
if(choice==1 && square[1]=='1')
square[1] = mark;
else if(choice==2 && square[2]=='2')
square[2] = mark;
else if(choice==3 && square[3]=='3')
square[3] = mark;
else if(choice==4 && square[4]=='4')
square[4] = mark;
else if(choice==5 && square[5]=='5')
square[5] = mark;
else if(choice==6 && square[6]=='6')
else if(choice==7 && square[7]=='7')
square[7] = mark;
else if(choice==8 && square[8]=='8')
square[8] = mark;
else if(choice==9 && square[9]=='9')
square[9] = mark;
else
{ // else statment OPEN
cout << "That is an invalid choice" <<endl;
player--;
cin.ignore();
cin.get();
} // else statement CLOSED
i=checkwin();
player ++;
} // do while loop CLOSED
while (i==-1);
board();
if(i==1)
cout << "==> Player " << --player << "win";
else
cout << "==> Game Draw" ;
cin.ignore();
cin.get();
return 0;
} // main function CLOSED
//****************************************************************
//**********************checkwin function *************************
//*****************************************************************
int checkwin()
{ // checkwin function bracket OPEN
if(square[1] == square[2] && square[2] == square[3])
return 1;
else if(square[4] == square[5] && square[5] == square [6] )
return 1;
else if(square[7] == square[8] && square[8] == square [9] )
return 1;
else if(square[1] == square[4] && square[4] == square[7])
return 1;
else if(square[2] == square[5] && square[5] == square[8])
return 1;
else if(square[3] == square[6] && square[6] == square[9])
return 1;
else if(square[1] == square[5] && square[5] == square[9])
return 1;
else if(square[3] == square[5] && square[5] == square[7])
return 1;
else if(square[1] != '1' && square[2] != '2' && square[3] != '3' && square[4] != '4'
&& square[5] != '5' && square[6] != '6' && square[7] != '7' && square[8] != '8'
&& square[9] != '9' )
return 0;
else
return -1;
} // checkwin function bracekt CLOSED
//*******************************************************************
//************************ board function ***************************
//*******************************************************************
void board()
{ // board function bracket OPEN
system("cls");
cout <<"\n\nTic Tac Toe\n\n";
cout<< "Player 1 ( X ) - Player 2 ( O )\n\n\n" ;
cout<< " | | " << endl;
cout<< " " << square[1] << " | " << square[2] << " | " << square[3] << endl;
cout<< "_____|_____|_____" << endl;
cout<< " | | " << endl;
cout<< " " << square[4] << " | " << square[5] << " | " << square[6] << endl;
cout<< "_____|_____|_____" << endl;
cout<< " | | " << endl;
cout<< " " << square[7] << " | " << square[8] << " | " << square[9] << endl;
cout<< " | | " << endl;
} // board function bracket CLOSED
Sorry if my question is a bit confusing or if I'm not being clear enough.
-1 in checkwin means that not all board fields are filled and no one wins at the moment, so game is not yet finished
1) at initial position, any square[i] != X or O
char square[10] {'0','1','2','3','4','5','6','7','8','9'}; or, equivalently,
square[0] = '0'; // dummy value -- not used at all
square[1] = '1';
square[2] = '2';
square[3] = '3';
square[4] = '4';
square[5] = '5';
square[6] = '6';
square[7] = '7';
square[8] = '8';
square[9] = '9';
2) they place mars on board mark =(player ==1) ? 'X' : 'O';
3) game contunues, while state of the game is -1:
do { // do while loop open
...
i=checkwin();
...
} while (i == -1)
-1 means that not all board fields are filled and no one wins at the moment, so game is not yet finished