How to handle spaces in strings

Hi everyone,

I'm writing code that uses an encoding called rot13, where each letter is shifted 13 spaces, so "a" becomes "n" and "b" becomes "o" etc. It was an old C assignment.

The problem:

When I enter Hello world, only hello is converted and not world.

Any ideas?

Code:

---

/*
Description: ROT13 encoding; to change each letter of a word 13 places along the alphabet. i.e, a
becomes n.
Input is from keyboard
modified date:26/11/04
*/

#include <stdio.h>
//#include <CLIB.H>    Commented out because it produces errors
#include <string.h>
main(){
  char rot13[100];
  int i=0;
     
  printf("Enter word  n ");
  scanf("%s",rot13);

  for(i=0;i<(strlen(rot13));i++)
  {
                               
      if (('a'<=rot13[i])&&(rot13[i]<='n'))
      {
              rot13[i]= rot13[i] + 13;
      }
      else if (('m'<=rot13[i])&&(rot13[i]<='z'))
      {
                      rot13[i]= rot13[i] - 13;
      }
      else if (('A'<=rot13[i])&&(rot13[i]<='N'))
      {
                      rot13[i]= rot13[i] + 13;
      }
      else if (('N'<=rot13[i])&&(rot13[i]<='Z'))
      {
                      rot13[i]= rot13[i] - 13;
      }                 
      else if (rot13[i]== 32)                                // 32 is ACSII for space
      {
                        rot13[i] = ' ';
                   
      }
    }

  printf("%s\n",rot13);
  system("PAUSE");                                            // There is a better away to stop the program from quiting, not sure what it is
 }

---

Maybe try fgets instead of scanf.

Quote:

---

Originally Posted by Epy

Maybe try fgets instead of scanf.

---

Or...

Code:

---

  char rot13[100];
  int i=0;
     
  printf("Enter word  n ");
  scanf("%99[^\n]",rot13);

---

Thanks Epy.

I haven't been able to find a good example of fgets and as far as I can see it only referes to reading data from files. Can you point me to a good example of fgets?

I'll keep looking into it. Thanks.

Brilliant hk_mp5kpdw, that worked.

I'm not sure what, 99[^\n] does though.

"%s", must only accept a string untill a space is pressed, so 99[^\n] must accept 99 charaters?

edit: %s is a type of Format Specifier for scanf:

C - printf and scanf, Format Specifiers

%[ABCD........XYZ] causes only the characters inside the brackets to be read by scanf ; if any other character is found then it terminates.

Oppositely in case of %[^\n]
the circumflex(^) causes every character to be read except the character inside the brackets, which becomes the terminating character.here \n is the terminating character.

So its a useful way for scanf sometimes.

Quote:

---

Originally Posted by a_satari

I'm not sure what, 99[^\n] does though.
C - printf and scanf, Format Specifiers

---

Because that documentation is unfortunately half-assed, and fails to mention a number of format specifiers such as the rather important []. Eg, to capture an alphanumeric string (no spaces, no punctuation):

Code:

---

scanf("%[a-zA-Z0-9]", string_ptr);

---

An example of fgets for user input:

Code:

---

char input[256];
fgets(input,256,stdin);

---

fgets() is very useful in combination with sscanf() -- notice, two ss -- since you can simply get all the input into a string, extract what you want from the string, and the then discard the rest, rather than messing around using scanf() on input directly.