Why won’t a chunck of this program run in Linux but will on Windows?

So I had to build a tiny little game that asks players to pick a number and see if they guess what the computer picks. It has 2 players and each can pass their turn to the other. One of the stipulations is that my professor is running a linux OS and has said if it doesn’t work on that then it’s a wash. When I run the code in codeblocks is works find and does exactly what it’s supposed to do. If a player passes and output message is displayed and the turn switches.

When I run the code on the linux server it always evaluates the turnInput of playTurn() as something other than “PASS” which returns the if(strcmp(turnInput, passValue) == 1) as false and moves to int turnInputNum = atoi(turnInput);

When I run it on codeblocks on windows it’s fine and does exactly what it should. when I compiled it I didn’t get any warnings and linux in and of itself is an OS I’ve really never dealt with before. Is there a reason why it would be passing over that code?

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <stdbool.h>

struct player{
    int passNum;
    int currentPassNum;
    bool myTurn;
};
    struct player player1;
    struct player player2;



    int turn = 1; //holds the games current turn
    int input; //holds the number input by player to indicate which player it is
    int RN; //holds Random Number
    int actualNum = -1; //signals completion of game by ending while loop

    void playTurn(void);
int main() {

    player1.currentPassNum = 0;
    player1.passNum = 0;
    player1.myTurn = true;
    player2.currentPassNum = 0;
    player2.passNum = 0;
    player2.myTurn = false;

    RN = generateRandom();


    while(RN != actualNum){
        printf("nEnter Player Number: ");
        scanf("%d", &input);
        if(input == turn){
            playTurn();
            if(turn == 1 && player1.myTurn == false){
                turn = 2;
            }
            else{
                turn = 1;
            }
        }
        else{
            printf("You have to wait your turn");
        }

    }



  return 0;
}

int generateRandom(){
    int n;

    srand(time(NULL));

    n = rand() % 100 + 1;

    return n;
}

void playTurn(){
    char turnInput[4];
    char passValue[4] = "PASS";
    int passes;

    printf("Enter your guess: ");
    scanf("%s", &turnInput);
        if(strcmp(turnInput, passValue) == 1){  <---- not running when PASS
            if(input == 1){
               if(player1.currentPassNum > 0){
                player1.currentPassNum = 0;
                player1.myTurn == true;
                printf("You may not pass!");
                return;
               }
               else{
                passes = player1.passNum;
                player1.passNum = player1.passNum + 1;
                player1.currentPassNum = 1;
                player1.myTurn = false;
                printf("Player 1 Passes to Player 2");
                return;
               }
            }
            if(input == 2){
                if(player2.currentPassNum > 0){
                player2.currentPassNum = 0;
                printf("You may not pass!");
                return;
               }
               else{
                passes = player2.passNum;
                player2.passNum++;
                player2.currentPassNum++;
                printf("Player 2 Passes to Player 1");
                return;

               }
            }
            if(passes > 3){
                printf("You can't pass anymore");
                return;
            }
        }
        int turnInputNum = atoi(turnInput); <---- Jumping to here every time
        if(turn == 1){
           player1.currentPassNum = 0;
           player1.myTurn = false;
        }
        else{
            player2.currentPassNum = 0;
            player1.myTurn = true;
        }
        if(turnInputNum > RN){
            printf("Too High");
            return;
        }
        if(turnInputNum < RN){
            printf("Too Low");
            return;
        }
        if(turnInputNum == RN){
            printf("CORRECT");
            actualNum = RN;
            return;
        }

}

Answer

strcmp has 3 possible return codes:

1. <0
2. ==0
3. >0

There is no specific ==1, and so it is not safe or portable to assume you can say ==1. Use >0 instead.

This is actually a pretty good example of portability and porting issues – from the question, apparently ==1 works on windows, but port that code to Linux and it stops. I’m not sure if windows documents “-1, 0, 1” or whether it was just an assumption that happened to work, but as OP found out: “Gotcha!!”