Thread: Remove space in a string

Well
your function parameter and local variable share the same name, so expect lots of fun there.
There's a spare ; at the end of your function definition
Why malloc only 30 ?
Why the casts in isspace
Those while loops will blow up if you try and trim a string containing only spaces

Here's a fun one:

Code:

    for( head=totrim, tail=totrim+(totrim?strlen(totrim)-1:0);
         head&&head!=tail;
         (isspace(*head)?head++:0),(isspace(*tail)?tail--:0) )
                if( !isspace( *head ) && !isspace( *tail ) )
                {
                        *++tail='\0';
                        break;
                }
        printf("\'%s\'\n", head ? head : "" );

[edit]
Hm... There's a very minor bug. Do you know what it is? Here's a hint, it's easily fixed, and will save one character of typing in fixing it. It will only occur in one specific case.
[/edit]

Quzah.

Originally Posted by alice

I want to change the function prototype to

Code:

int trimString(char* str);

am my code correct? thk a lot.

No

Code:

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int trimString(char* str);
{
  char *str = malloc(30);   // redefinition of str.  Try the statement below
  char *p, *end;
  str = malloc(30); // this is in the proper place 

  *str = '\0';   // Why?  Just use strcpy() instead 
  strcat(str, "   abcd  EFGH   ");
  end = str + (strlen(str) - 1);
  while (isspace((unsigned char)*end)) {
    --end;
  }
  *++end = '\0';
  p = str;
  while (isspace((unsigned char)*p)) {
    ++p;
  }
  puts(p);
  free(p);    // Confusing and wrong.  You malloc'd str so release str 

  return 0;
}

[edit]
Oh, and why are you passing in the pointer to str and then throwing away everything it points to? For testing wouldn't it be better to do:

Code:

int main()
{
    char *str;

    str = malloc(30);
    strcpy(str, "   abcd  EFGH   ");
    int trimString(str);
    free(str);
    return 0;
}

int trimString(char* str);
{
    char *end, p;

    end = str + (strlen(str) - 1);
    while (isspace((unsigned char)*end)) 
    {
        --end;
    }
    *++end = '\0';
    p = str;
    while (isspace((unsigned char)*p)) 
    {
        ++p;
    }
    puts(p);
    return 0;
}

The fact that you are changing str can be dealt with next, when you pass back the new string instead of outputting it in the function.
[/edit]

> My compiler give error "Declaration is not allowed here"
> on the line ''int trimString(str);''
Yeah, see what I said 2 days ago

Code:

int trimString(char* str);
{

That's because there's one tiny character extra...*

On an aside, I see no one spotted the bug in my code. It has to do with !=. The bug will show itself if you pass the function " " (two white spaces) as your string. That's the only time it will happen. Like I said, very small, extremely rare occurance, but there none the less. Chaning it to a less-than fixes solves the problem.

Quzah.
*[edit]Curses, foiled again![/edit]