Connect four game, if statement - c

Question

Here is code for my connect four game for exam. There are seven columns, if a number above 7 is entered it should say "Move not allowed", but if 0 is entered it should save the game.
When I enter 0 it says "Move not allowed". There is a code to save the game when 0 is entered but it says "Move not allowed" and doesn't go there. Can someone help?
#include <stdio.h>
#include <string.h>
typedef struct gameState{
int id;
char board[6][7];
int numberOfMoves;
char player1Name[20];
char player2Name[20];
}GameState;
void ShowMenu() {
printf("\n\n\n1. New Game \n");
printf("2. Load Game \n");
printf("3. Exit \n\n");
printf("Choose: ");
}
void ReadPlayerNames(char player1Name[20], char player2Name[20]) {
printf("\nName of first player:");
scanf("%s", player1Name);
printf("\nName of second player:");
scanf("%s", player2Name);
}
void PrintBoard(char board[6][7])
{
char header[] = " 1 2 3 4 5 6 7 ";
char border[] = "|---|---|---|---|---|---|---|";
printf("%s\n", header);
printf("%s\n", border);
for (int i = 0; i < 6; i++)
{
for (int j = 0; j < 7; j++)
{
printf("| %c ", board[i][j]);
}
printf("|\n");
printf("%s\n", border);
}
}
void ClearBoard(char board[6][7]) {
for (int i = 0; i < 6; i++){
for (int j = 0; j < 7; j++) {
board[i][j] = ' ';
}
}
}
// 1 - X wins, 2 - O wins, 0 - still playing
int CheckDiagonals(char board[6][7], int i, int j, int goUpRight){
int connectedO = 0;
int connectedX = 0;
while(i >= 0){
if (board[i][j] != ' '){
if (board[i][j] == 'X'){
connectedX++;
connectedO = 0;
if (connectedX == 4){
if (goUpRight = 0){
board[i][j] = 'Y'; //checking if x won, putting Y on places of x
board[i + 1][j + 1] = 'Y';
board[i + 2][j + 2] = 'Y';
board[i + 3][j + 3] = 'Y';
} else {
board[i][j] = 'Y';
board[i + 1][j - 1] = 'Y';
board[i + 2][j - 2] = 'Y';
board[i + 3][j - 3] = 'Y';
}
return 1;
}
} else {
connectedO++;
connectedX = 0;
if (connectedO == 4){
if (goUpRight = 0){
board[i][j] = 'Y';
board[i + 1][j + 1] = 'Y'; //checking if o won, putting Y on places of o
board[i + 2][j + 2] = 'Y';
board[i + 3][j + 3] = 'Y';
} else {
board[i][j] = 'Y';
board[i + 1][j - 1] = 'Y';
board[i + 2][j - 2] = 'Y';
board[i + 3][j - 3] = 'Y';
}
return 2;
}
}
} else {
connectedO = 0;
connectedX = 0;
}
i--;
if (goUpRight == 1){
j++;
}else{
j--;
}
}
return 0;
}
// 1 - X wins, 2 - O wins, 0 - still playing
int CheckRowsOrCols(char board[6][7], int rows){
int connectedO = 0;
int connectedX = 0;
int brI = 6;
int brJ = 7;
if (rows == 0){
brI = 7;
brJ = 6;
}
for (int i = 0; i < brI; i++){
for (int j = 0; j < brJ; j++) {
int pI = i, pJ = j;
if (rows == 0){
pI = j;
pJ = i;
}
if (board[pI][pJ] != ' '){
if (board[pI][pJ] == 'X'){
connectedX++;
connectedO = 0;
if (connectedX == 4){
if (rows == 0){
board[pI][pJ] = 'Y';
board[pI - 1][pJ] = 'Y';
board[pI - 2][pJ] = 'Y';
board[pI - 3][pJ] = 'Y';
} else {
board[pI][pJ] = 'Y';
board[pI][pJ - 1] = 'Y';
board[pI][pJ - 2] = 'Y';
board[pI][pJ - 3] = 'Y';
}
return 1;
}
} else {
connectedO++;
connectedX = 0;
if (connectedO == 4){
if (rows == 0){
board[pI][pJ] = 'Y';
board[pI - 1][pJ] = 'Y';
board[pI - 2][pJ] = 'Y';
board[pI - 3][pJ] = 'Y';
} else {
board[pI][pJ] = 'Y';
board[pI][pJ - 1] = 'Y';
board[pI][pJ - 2] = 'Y';
board[pI][pJ - 3] = 'Y';
}
return 2;
}
}
} else {
connectedO = 0;
connectedX = 0;
}
}
}
return 0;
}
// 1 - X wins, 2 - O wins, 0 - still playing
int CheckForWinner(char board[6][7]) {
int rezultat = CheckRowsOrCols(board, 1);
if (rezultat != 0){
return rezultat;
}
rezultat = CheckRowsOrCols(board, 0);
if (rezultat != 0){
return rezultat;
}
for (int i = 0; i < 6; i++){
rezultat = CheckDiagonals(board, i, 0, 1);
if (rezultat != 0){
return rezultat;
}
}
for (int j = 0; j < 7; j++){
rezultat = CheckDiagonals(board, 5, j, 1);
if (rezultat != 0){
return rezultat;
}
rezultat = CheckDiagonals(board, 5, j, 0);
if (rezultat != 0){
return rezultat;
}
}
for (int i = 0; i < 6; i++){
rezultat = CheckDiagonals(board, i, 6, 0);
if (rezultat != 0){
return rezultat;
}
}
return 0;
}
void SaveGame(char board[6][7], int movesPlayed, char player1Name[20], char player2Name[20]){
printf("\n\n\nEnter ID for your game: ");
int id;
scanf("%d", &id);
GameState state;
state.id = id;
for (int i = 0; i < 6; i++){
for (int j = 0; j < 7; j++){
state.board[i][j] = board[i][j];
}
}
state.numberOfMoves = movesPlayed;
strcpy(state.player1Name, player1Name);
strcpy(state.player2Name, player2Name);
FILE *filePointer;
filePointer = fopen("SavedGames.dat", "ab");
if (filePointer == NULL){
printf("\nGames not found!");
return;
}
fwrite(&state, sizeof(state), 1, filePointer);
fclose(filePointer);
printf("\nGame with ID:%d saved!", id);
}
int MakeMove(char board[6][7], int movesPlayed, char player1Name[20], char player2Name[20]) {
char sign = 'X';
if (movesPlayed % 2 == 1){
sign = 'O';
}
int column;
while (1){
printf("\nChoose the column player %c(0 for save and exit): ", sign);
column;
scanf("%d", &column);
if (column >= 0 && column <= 7 && board[0][column-1] == ' '){
break;
}
printf("\nMove not allowed!\n");
}
if (column != 0){
for (int i = 6; i >= 0; i--) {
if (board[i][column-1] == ' ') {
board[i][column-1] = sign;
printf("\n\n\n");
break;
}
}
}else {
SaveGame(board, movesPlayed, player1Name, player2Name);
return 1;
}
return 0;
}
void PlayGame(char board[6][7], char player1Name[20], char player2Name[20], int movesPlayed){
while (1){
PrintBoard(board);
if (MakeMove(board, movesPlayed, player1Name, player2Name) == 1){
break;
}
movesPlayed++;
int result = CheckForWinner(board);
if (result != 0){
PrintBoard(board);
if (result == 1){
printf("\nX wins\n\n\n");
} else {
printf("\nO wins\n\n\n");
}
break;
}
if (movesPlayed == 42){
PrintBoard(board);
printf("\nTie!\n\n\n");
break;
}
}
}
void ListAllSavedGames(){
FILE *filePointer;
filePointer = fopen("SavedGames.dat", "rb");
if (filePointer == NULL){
printf("\nGames not played yet!");
return;
}
GameState state;
while(fread(&state, sizeof(state), 1, filePointer) == 1){
printf("\n%d, X: %s, O: %s, %d", state.id, state.player1Name, state.player2Name, (42 - state.numberOfMoves));
}
fclose(filePointer);
}
void ListAllPlayerGames(){
char playerName[20];
printf("\nName of player: ");
scanf("%s", playerName);
FILE *filePointer;
filePointer = fopen("SavedGames.dat", "rb");
if (filePointer == NULL){
printf("\nGames not played yet!");
return;
}
GameState state;
while(fread(&state, sizeof(state), 1, filePointer) == 1){
if (strcmp(playerName, state.player1Name) == 0 || strcmp(playerName, state.player2Name) == 0){
printf("\n%d, X: %s, O: %s, %d", state.id, state.player1Name, state.player2Name, (42 - state.numberOfMoves));
}
}
fclose(filePointer);
}
int ShowTheBoard(){
int ID;
printf("\nEnter ID: ");
scanf("%d", &ID);
FILE *filePointer;
filePointer = fopen("SavedGames.dat", "rb");
if (filePointer == NULL){
printf("\nGames not played yet!");
return;
}
int IDfound = 0;
GameState state;
while(fread(&state, sizeof(state), 1, filePointer) == 1){
if (ID == state.id){
IDfound = 1;
printf("\nX: %s, O: %s", state.player1Name, state.player2Name);
PrintBoard(state.board);
}
}
fclose(filePointer);
if (IDfound == 0){
return 1;
}
return 0;
}
int LoadAGame(){
int ID;
printf("\nEnter ID: ");
scanf("%d", &ID);
FILE *filePointer;
filePointer = fopen("SavedGames.dat", "rb");
if (filePointer == NULL){
printf("\nGames not played yet!");
return;
}
int IDfound = 0;
GameState state;
while(fread(&state, sizeof(state), 1, filePointer) == 1){
if (ID == state.id){
IDfound = 1;
PlayGame(state.board, state.player1Name, state.player2Name, state.numberOfMoves);
}
}
fclose(filePointer);
if (IDfound == 0){
return 1;
}
return 0;
}
void ShowLoadMenu(){
int returnToMainMenu = 0;
while (returnToMainMenu == 0){
printf("\n\n\n1. List all saved games\n");
printf("2. List all saved games for a particular player\n");
printf("3. Show the board of one of the saved games\n");
printf("4. Load a game\n");
printf("5. Return to main menu\n");
printf("Choose: ");
int choice;
scanf("%d", &choice);
switch(choice){
case 1:
ListAllSavedGames();
break;
case 2:
ListAllPlayerGames();
break;
case 3:
while (ShowTheBoard() == 1){
printf("ID not valid!");
}
break;
case 4:
while (LoadAGame() == 1){
printf("ID not valid!");
}
returnToMainMenu = 1;
break;
case 5:
returnToMainMenu = 1;
break;
default:
printf("Wrong choice, try again!");
}
}
}
int main(){
int endOfProgram = 0;
while (endOfProgram == 0){
char board[6][7];
char player1Name[20];
char player2Name[20];
int movesPlayed = 0;
ShowMenu();
int choice;
scanf("%d", &choice);
switch(choice){
case 1:
ClearBoard(board);
ReadPlayerNames(player1Name, player2Name);
PlayGame(board, player1Name, player2Name, movesPlayed);
break;
case 2:
ShowLoadMenu();
break;
case 3:
printf("Goodbye!");
endOfProgram = 1;
break;
default:
printf("Wrong choice, try again!");
}
}
}

Answer 1

Culprit is likely to be inside MakeMove:
if (column >= 0 && column <= 7 && board[0][column-1] == ' ') {
break;
}
if you pass 0 as column, the first 2 tests will indeed succeed (both 0 >= 0 and 0 <= 7 are true). But third one tries to use board[0][-1]. -1 is not a valid index and you are invoking UB.
If column is 0, you should not test anything else, so your test should be:
if (column == 0 || (column > 0 && column <= 7
&& board[0][column-1] == ' ')) {
break;
}