My Do-While loop doesn't seem to loop? - c

Question

Please help, I cant seem to get the do-while loop to loop when I ask the user to input continue using scanf and printf. Could it be the wipe_buffer? I can't seem to get it right on this and I just need to finish the loop and that should be mostly functional. New to coding and this website please not too harsh. please and thanks.
#include <stdio.h>
#include <stdlib.h>
void wipe_buffer(void);
int main(int argc, char* argv[])
{
char play1;
char play2;
char cont;
do{
printf("Player one pick Rock, Paper, or Scissors\n");
scanf(" %c", &play1);
wipe_buffer();
printf("Player two pick Rock, Paper, or Scissors\n");
scanf(" %c", &play2);
wipe_buffer();
switch(play1)
{
case 'r':
if(play2 == 'p' || play2 == 'P')
{
printf("Paper Covers Rock\n");
printf("Player two wins\n");
}
if(play2 == 's' || play2 == 'S')
{
printf("Rock Breaks Scissors\n");
printf("Player one wins\n");
}
if(play2 == 'r' || play2 == 'R')
{
printf("Draw, Nobody wins\n");
}
break;
case 'R':
if(play2 == 'p' || play2 == 'P')
{
printf("Paper Covers Rock\n");
printf("Player two wins\n");
}
if(play2 == 's' || play2 == 'S')
{
printf("Rock Breaks Scissors\n");
printf("Player one wins\n");
}
if(play2 == 'r' || play2 == 'R')
{
printf("Draw, Nobody wins\n");
}
break;
case 'P':
if(play2 == 'p' || play2 == 'P')
{
printf("Draw, Nobody wins\n");
}
if(play2 == 's' || play2 == 'S')
{
printf("Scissors cuts Paper\n");
printf("Player two wins\n");
}
if(play2 == 'r' || play2 == 'R')
{
printf("Paper covers rock\n");
}
break;
case 'p':
if(play2 == 'p' || play2 == 'P')
{
printf("Draw, Nobody wins\n");
}
if(play2 == 's' || play2 == 'S')
{
printf("Scissors cuts Paper\n");
printf("Player two wins\n");
}
if(play2 == 'r' || play2 == 'R')
{
printf("Paper covers rock\n");
}
break;
case 's':
if(play2 == 'p' || play2 == 'P')
{
printf("Scissors Cuts Paper\n");
printf("Player one wins\n");
}
if(play2 == 's' || play2 == 'S')
{
printf("Draw, Nobody wins\n");
}
if(play2 == 'r' || play2 == 'R')
{
printf("Rock breaks Scissors\n");
printf("Player two wins\n");
}
break;
case 'S':
if(play2 == 'p' || play2 == 'P')
{
printf("Scissors Cuts Paper\n");
printf("Player one wins\n");
}
if(play2 == 's' || play2 == 'S')
{
printf("Draw, Nobody wins\n");
}
if(play2 == 'r' || play2 == 'R')
{
printf("Rock breaks Scissors\n");
printf("Player two wins\n");
}
break;
}
printf("Do you wish to continue?\n");
scanf(" &c", &cont);
wipe_buffer();
}while(cont == 'y' || cont == 'Y');
}
void wipe_buffer(void)
{
char t;
scanf("%c", &t);
while(t != '\n' )
{
scanf("%c", &t);
}
return;
}

Answer 1

In this section:
printf("Do you wish to continue?\n");
scanf(" &c", &cont);
"&c" should be "%c"
Note that when I compiled this with gcc, I got a warning that basically addressed this exact problem, so make sure to read your warnings.

Answer 2

In here:
printf("Do you wish to continue?\n");
scanf(" &c", &cont);
wipe_buffer();
}while(cont == 'y' || cont == 'Y');
there should be:
scanf(" %c", &cont);
Compile with -Wall -pedantic options next time you face some problem(if you use gcc).
It shows nicely where the problem lies, and if not - it narrows it down a little.
That's what it shows in your case:
test2.c:117:5: warning: too many arguments for format [-Wformat-extra-args]
test2.c:120:1: warning: control reaches end of non-void function [-Wreturn-type]
so it's also a nice reminder that your main() function has to return some value.
Another suggestion is to rad through this link:http://www.gidnetwork.com/b-60.html
and follow to The Steps page.
To make it short - there's some information on how time and space consuming is reading one char from stdin with scanf in comparison to getchar.
Consider applying this suggestion in your code.

Answer 3

So, a really quick way to see what's going on is to drop a debugging printf statement right before the loop
scanf(" &c", &cont);
wipe_buffer();
printf("Debug: [%c]\n", cont);
}while(cont == 'y' || cont == 'Y');
Then look for the printf when the program runs.
I think what is going on is that each scanf is looking for a Enter keystroke before processing, so wipe_buffer is going to request a lot of Enter keystrokes before continuing. Try running the program without the wipe_buffer and you'll still need to press Enter before it continues.