Thread: Printf issue I've never encountered before...

So I'm adding an extra menu to my program and one of the printf statements decides to double print its output, something I have never seen before. I tried changing around some of the variable names, but none of that helped. If I changed it to some random output i.e. "asdghagkgklshklgh" it did not double print. Everything is in the string quotes so I'm not sure whats going on. Any help would be awesome.

Code:

void SetupMenu(){


int DISTMOON, FUEL, NEWFFALL;
char READY;
float VELOCITY;


printf("* * * * * * * Setup Menu  * * * * * * * * *\n\n");
printf("Allows user to change Moon lander initial\n");
printf("values for a whole new experience !!!\n\n");
printf("* * * * * * * * * * * * * * * * * * * * * *\n\n");


READY = 'N';


   while (!(READY == 'Y')){
      do {
         printf("Enter new distance to Moon:  >>");
         scanf("%d", &DISTMOON);
      } while (DISTMOON <= 0);


      do {
         printf("Enter new amount of fuel:    >>");
         scanf("%d", &FUEL);
      } while (FUEL <= 0);


      printf("Enter new velocity of ship:  >>");
      scanf("%f", &VELOCITY);


      do {
         printf("Enter new Moon gravity:      >>");
         scanf("%d", &NEWFFALL);
      } while (FFALL <= 0);


      do {
         printf("Ready (Y/N)?      >>");
         scanf("%c", &READY);
      } while ((READY != 'Y') && (READY != 'N'));
   }


return;
}

> one of the printf statements decides to double print its output
Which one?

> I tried changing around some of the variable names, but none of that helped
That will never fix the problem.

Edit: where's FFALL defined? You're checking it with NEWFFALL instead, so it does this infinitely.

I didn't get any garbage value printed,the only problem is the scanf part.

Thanks for the advice, haven't tested any of your guys implementations yet though. The double print I was getting was on the ready printf statement.

Got it working it was definitely the space before the % as was mentioned... although I'm not sure the reason why exactly that was needed. Care to elaborate?

Thanks. Appreciate the help.

%c will read the next character, even if it's just a space or a newline.
Putting a space before %c causes printf to consume all whitespace before reading the next character.

But it wasn't in printf it was in scanf. Printf doubled its output because of something linked to scanf?