Assign constant char to another char variable

**effup** · 10-04-2012

Hi all,
I'm having trouble with my project (connect 4). At the beginning of the program I define 2 constants char that represents black checker and red checker as follows:

#define RED 'X'
#define BLACK 'O'

I have a menu() function that prints out welcome to the game, stuff like that. I then proceed to ask the user which color he would like to be, then assign it to one of the constant char (RED or BLACK) appropriately as follows:

Code:

int choice;
char player;
char com;
scanf("so you wan to be... %d \n", &choice);
	if (choice == 1) {
		player = RED;
		com = BLACK;
		
	}
	
	else if (choice == 2) {
		player = BLACK;
		com = RED;
		
	}

I then prints out char player and char com to confirm that I have assigned the values correctly:
printf("the player chose to be: %c\n", player);
but this only prints out "the player chose to be: "
what am I doing wrong here ? Any suggestion would be greatly appreciated. Thanks in advance everyone !

**Click_here** · 10-04-2012

Code:

scanf("so you wan to be... %d \n", &choice);


should be more like


puts("so you wan to be...");
scanf("%d%*c", &choice); // (%*c for when the user hits enter)

**effup** · 10-04-2012

Thank you for the prompt reply, but can you please elaborate a bit (I'm very new to C) ? So %*c is a pointer right ?

**Click_here** · 10-04-2012

In the context of scanf - When you put a '*' after the %, it will read the input and do nothing with it

i.e.

Code:

scanf("%d%*c", &choice);

%d - This would read the first input part as a number and put it into choice
%*c - This would read a character and then do nothing with it.

Here is a full list of all the things you can do with scanf (for windows)
- Format Specification Fields: scanf and wscanf Functions (CRT)
- scanf Width Specification (CRT)
- scanf Type Field Characters (CRT)

**oogabooga** · 10-04-2012

Nope. The stuff that appears between quotes as the first parameter of scanf is a mini-language specific to scanf, so the asterisk is not related to pointers at all.

%c means to read a character and assign it to a given address.
%*c means to read a character and then just throw it away (ignore it).
The * can be used with any of the specifiers to indicate that the data is to be read and then thrown away.

So, e.g.,
scanf("%d%*d%d", &n, &m);
Reads an integer and assignes it to n,
read another integer and ignores it,
reads another integer and assignes it to m.

In the case at hand, click_here has used %*c in an attempt to "eat" the newline so it won't be left in the stream. It's not foolproof (someone might type an extra space before the newline), but it usually works.

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