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Full Discussion: How to trim the white space around a string in C program
Top Forums Programming How to trim the white space around a string in C program Post 302248304 by calv on Friday 17th of October 2008 09:05:54 AM
Old 10-17-2008
error in trim_copy() was a typo: "ouput" -> "output" (but no segfault)

error in trim_nocopy() was an undeclared variable (that also needs to be initialized. segfault, if the new variable is not initialized and the string contains no nonspace characters)

btw. trim_nocopy() has no real practical reason to exist. It is only to show that a left trimming can be done without writing to the string at all, just by changing the start pointer. Also right trimming can be done by just writing a zero after the last nonspace. In fact the trim_copy() function is the one you should always use, both for in place (input==output) or copying operations. Also it makes sense to switch the parameters, so they are in sync with other c std lib string functions like strcpy() and strcat().

ok, now the fixed version:

Code:
void trim_copy(char *input, char *output)
{
  char *end = output;
  char c;

  // skip spaces at start
  while(*input && isspace(*input))
    ++input;

  // copy the rest while remembering the last non-whitespace
  while(*input)
  {
    // copy character
    c = *(output++) = *(input++);

    // if its not a whitespace, this *could* be the last character
    if( !isspace(c) )
      end = output;
  }

  // write the terminating zero after last non-whitespace
  *end = 0;
}

void trim_inplace(char *s)
{
  trim_copy(s, s);
}

char *trim_nocopy(char *s)
{
  char *start = s;

   // skip spaces at start
  while(*start && isspace(*start))
    ++start;

  char *i = start;
  char *end = start;
  // iterate over the rest remebering last non-whitespace
  while(*i)
  {
    if( !isspace(*(i++)) )
      end = i;
  }

  // write the terminating zero after last non-whitespace
  *end = 0;

  return start;
}

 

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LEARN ABOUT DEBIAN

git-stripspace

GIT-STRIPSPACE(1)						    Git Manual							 GIT-STRIPSPACE(1)

NAME

       git-stripspace - Remove unnecessary whitespace

SYNOPSIS

       git stripspace [-s | --strip-comments] < input

DESCRIPTION

       Clean the input in the manner used by git for text such as commit messages, notes, tags and branch descriptions.

       With no arguments, this will:

       o   remove trailing whitespace from all lines

       o   collapse multiple consecutive empty lines into one empty line

       o   remove empty lines from the beginning and end of the input

       o   add a missing 
 to the last line if necessary.

       In the case where the input consists entirely of whitespace characters, no output will be produced.

       NOTE: This is intended for cleaning metadata, prefer the --whitespace=fix mode of git-apply(1) for correcting whitespace of patches or
       files in the repository.

OPTIONS

       -s, --strip-comments
	   Skip and remove all lines starting with #.

EXAMPLES

       Given the following noisy input with $ indicating the end of a line:

	   |A brief introduction   $
	   |   $
	   |$
	   |A new paragraph$
	   |# with a commented-out line    $
	   |explaining lots of stuff.$
	   |$
	   |# An old paragraph, also commented-out. $
	   |	  $
	   |The end.$
	   |  $

       Use git stripspace with no arguments to obtain:

	   |A brief introduction$
	   |$
	   |A new paragraph$
	   |# with a commented-out line$
	   |explaining lots of stuff.$
	   |$
	   |# An old paragraph, also commented-out.$
	   |$
	   |The end.$

       Use git stripspace --strip-comments to obtain:

	   |A brief introduction$
	   |$
	   |A new paragraph$
	   |explaining lots of stuff.$
	   |$
	   |The end.$

GIT

       Part of the git(1) suite

Git 1.7.10.4							    11/24/2012							 GIT-STRIPSPACE(1)
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