Thread: issues working with two-dimensional array

Hi--I'm trying to implement Conway's Game of Life on a 10x10 board (with borders), and I'm having a bit of trouble. At this point, it seems most likely that said trouble lies in either my display function or the for loop I use to call it in main, so here's the code in question:

Code:

void display_life(char life[12][12]){
	int row, column, status;
	char enter;
	printf("\n\n");
	for(row=0; row<=11; row++){
		for(column=0; column<=11; column++){
			printf("&#37;c", life[row][column]);
			if(column==11){
				printf("\n");
			}//if column==11
		}//for column
	}//for row
	do{
		printf("\nPress the Enter key to continue.");
		status=scanf("%c", &enter);
	}while(status!=1);
} //displays the life board and waits for the user to press the Enter key.

int main(){
	char life[12][12];
	int count, status;
	init_life(life);
	display_life(life);
	for(count=1; count<9; count++){
		update_life(life);
	}//for(count=0; count<10; count++)*/
	return 0;
}//main

Now, as far as I can tell, display_life should wait for the user to press return before main moves on to the for loop, but this is the output I get on running the program:

Code:

teyla:~ quasigreat$ ~quasigreat/a.out
Please enter the file name>> Life1.dat


|__________|
|XXXXXXXXXX|
|          |
|XXXXXXXXXX|
|XXXXXXXXXX|
|          |
|XXXXXXXXXX|
|XXXXXXXXXX|
|XXXXXXXXXX|
|          |
|XXXXXXXXXX|
|__________|

Press the Enter key to continue.

|__________|
|X         |
|          |
|          |
|          |
|          |
|          |
|          |
|          |
|          |
|          |
|__________|

Press the Enter key to continue.

To clarify, it displays the second board without waiting for keyboard input. Any help would be much appreciated. (I might even offer to sacrifice my firstborn. You never know.)

>Please enter the file name>> Life1.dat
You probably have a newline left in the input buffer after the user enters the file name, which is subsequently read by this call to scanf:
> status=scanf("%c", &enter);
One solution is to add the following code after the user enters the file name:

Code:

while (getchar() != '\n');

Another solution is to use fgets() to read the file name entered by the user.

Thank you! It's fixed now.

I wonder if I might trouble you further to take a look at my update_life function, as it doesn't seem to be working. It's meant to count the number of Xs in neighboring cells and apply the rules accordingly, but I'm getting the output shown in my original post--one sad little X in the upper left corner. I've separated out the block that applies the rules and highlighted the comments, in an attempt to make it a little easier to read:

Code:

void update_life(char life[12][12]){ 
	char new_life[12][12];
	int row, column, count;
	for(row=1; row<=10; row++){
		for(column=1; column<=10; column++){
			if(life[row-1][column-1]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor up and to the left
			if(life[row][column-1]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor to the left
			if(life[row+1][column-1]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor down and to the left
			if(life[row-1][column]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor above
			if(life[row+1][column]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor below
			if(life[row-1][column+1]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor above and to the right
			if(life[row][column+1]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor to the right
			if(life[row+1][column+1]=='X'){
				count++;
			} else {
				count=count;
			}//check neighbor below and to the right
			
			if(life[row][column]==' ' && count==3){
				new_life[row][column]='X'; //birth
			} else if(life[row][column]=='X' && count>=2 && count<=3){
				new_life[row][column]='X'; //survival
			} else if(life[row][column]=='X' && (count<2 || count>3)){
				new_life[row][column]=' '; //death
			} else {
				new_life[row][column]=life[row][column];
			}
			
		}//for column
	}//for row
	for(row=1; row<=10; row++){
		for(column=1; column<=10; column++){
			life[row][column]=new_life[row][column];
		}//for column
	}//for row
	display_life(life);
}

>It's meant to count the number of Xs in neighboring cells and apply the rules accordingly,
One problem I see is you never initialize count to 0 at the start of the if() checks. Also, while it doesn't do any harm, all of the:

Code:

} else {
	count=count;
}

statements are unnecessary, as count will by default keep it previous value.