Problem with reading and printing a character

hubabuba · 02-28-2005, 09:09 AM

Hi there!

Have a little program for the exercise i'm doing, where I have to enter a number and a character and the program will print the character entered number of times in a line and the same number of lines. So if i enter 3 and enter the character '#", the program will print:

###
###
###

The problem though, is that after i enter the number, program will not let me enter a character and just terminates looking like this:

[root@dhcppc0 prog]# ./program
Enter the square's side:2
Enter a character:

[root@dhcppc0 prog]#

The code of the program:

Code:

#include <stdio.h>

void square(int side, char fillCharacter);

int main()
{
  int a;
  char c;
  
  printf("Enter the square's side:");
  scanf("%d", &a);
  printf("Enter a character: ");
  scanf("%c", &c);
    
  square(a, c);
  
  return 0;
}

void square(int side, char fillCharacter)
{
  int width, height;
  
  for(height = 1; height <= side; height++)
  {
    for(width = 1; width <= side; width++)
    {
      printf("%c", fillCharacter);
    
      if(width == side)
        printf("\n");
    }
  }   
}

Thanks

ortho-orange#42 · 02-28-2005, 10:05 AM

Code:

#include <stdio.h>

void square(int side, char fillCharacter);

int main()
{
  int a;
  char c;
  
  printf("Enter the square's side:");
  scanf("%d", &a);
  printf("Enter a character: ");
  scanf("%c", &c);
    
  square(a, c);
  
  return 0;
}
<snip>
}

I've never been able to store scanf's results in an int, or char (maybe my own lack of experience). however, you can define a temporary char pointer

Code:

char *s;
char *c;

pass that to scanf:

Code:

scanf("%s", s);   // get squares side
scanf("%s", c);  // get character

and then use atoi to convert that to an int.

Code:

a=atoi(s);

Then, only pass the first element of the string to your square function.

Code:

square(a, c[0]);

Also, you'll need to include stdlib.h.
This worked for me, but not being too big into C, there's probably better, or more correct ways to do it. Unless I changed something and forgot, your square function is, well...functional

HTH

hubabuba · 02-28-2005, 11:09 AM

The program is now working, all I had to do is to put a space between double quote and the remainder operator in the scanf expression like this:

Code:

scanf(" %c", &c);

instead of:

Code:

scanf("%c", &c);

, but I don't understand why this made it work

Can anyone explain?

thanks

Hko · 02-28-2005, 02:41 PM

When the first scanf() runs, you press ENTER to submit the number you just typed. The ENTER puts a newline character ('\n') in the input buffer, and still needs to be "read away" before scanf() will read the next item. This is so because scanf() expects whitespace (one or more spaces, tabs, or newlines) between items.

When you put a space in scanf()'s format string, this tells scanf() to "read away" any whitespace, after which it will accept the next item. In your case this next item will be the char (%c).

I don't like scanf()....