getchar() error?

This code is pretty self-explanatory. its supposed to read in a character and write the next character as its output. However i seem to be getting NOT that effect. The code from the book compiles and runs fine and i swear mine is the same but it works differently.

Code:

/* ch7listing7.2. getchar() */

#include <stdio.h>
#define space ' '
int main(void){
  char ch;

  while ((ch=getchar()) !='\n'){
     if (ch == space){
        putchar(ch);
     }

     else
        putchar(ch + 1);
     ch = getchar();
  }

  putchar(ch);
  return 0;
 }

try this

Code:

#include <stdio.h>

#define space ' '

int main(void)
{
    char ch = 0;

    while ((ch = getchar()) != EOF) {
	if (ch == space) {
	    putchar(ch);
	}

	else
	    putchar(ch + 1);
    }

    putchar(ch);
    return 0;
}

~/

So: what does your code do? What do you expect it to do?

It does pretty much what I expect it to do, but I don't have your book, so my expectations weren't tainted by high hopes.

Dave

Originally posted by Dave Evans
So: what does your code do? What do you expect it to do?

It does pretty much what I expect it to do, but I don't have your book, so my expectations weren't tainted by high hopes.

Dave

The code is supposed to output ch + 1 for whatever character you enter ex:

input: abcde
ouptut:bcdef

it outputs the first character correctly and subsequent charactes seemingly random.


kermit: your code works up to a the last character, where it ouputs a characer I don't know. Try it and see.
ex: abcdef
out: bcdefg^

Originally posted by caroundw5h
The code is supposed to output ch + 1 for whatever character you enter ex:

input: abcde
ouptut:bcdef

The original code had two getchar() calls in the loop, and, therefore skipped every other character. (One getchar() in the while() part, and one getchar() at the bottom of the loop. Get rid of the second one. It seems to work as advertised now, at least for the test string you supplied.

Dave

Originally posted by Dave Evans
The original code had two getchar() calls in the loop, and, therefore skipped every other character. (One getchar() in the while() part, and one getchar() at the bottom of the loop. Get rid of the second one. It seems to work as advertised now, at least for the test string you supplied.

Dave

This is the books code

Code:

/* cypher1.c -- alters input, preserving spaces */
#include <stdio.h>
#define SPACE ' '             /* that's quote-space-quote */
int main(void)
{
   char ch;

   ch = getchar();            /* read a character         */
   while (ch != '\n')         /* while not end of line    */
   {
       if (ch == SPACE)       /* leave the space          */
           putchar(ch);       /* character unchanged      */
       else
           putchar(ch + 1);   /* change other characters  */
       ch = getchar();        /* get next character       */
   }
   putchar(ch);
   getchar();              /* print the newline        */
   return 0;
}

and it works fine. I'm wondering if there is something i'm missing because i've been looking at it too long.

your code (from first post):

Code:

 while ((ch=getchar()) !='\n'){
     if (ch == space){
        putchar(ch);
     }

     else
        putchar(ch + 1);
     ch = getchar();
  }

Two getchar() per loop

book's code (from your last post)

Code:

 ch = getchar();            /* read a character         */
   while (ch != '\n')         /* while not end of line    */
   {
       if (ch == SPACE)       /* leave the space          */
           putchar(ch);       /* character unchanged      */
       else
           putchar(ch + 1);   /* change other characters  */
       ch = getchar();        /* get next character       */
   }

one getchar() per loop

You don't see the difference?

Dave

Yeah, i'm a dumbass, I changed the code and not properly. Trying to make it more succint.

[edit]

Code:

#include <stdio.h>
#define space ' '
int main(void){
   char ch;
  while ((ch=getchar()) != '\n'){
     ch = (ch == space) ? putchar(ch) : putchar (ch + 1);
  }

  putchar(ch);
  getchar();
  return 0;
 }[/edit]