Sponsored Content
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;
}

 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

How to trim space in output variable ?

Hi , I have a code like this: uid=scott password=tiger database=db01 cat >runid_val.sql<<-EOA SET ECHO OFF SET FEEDBACK OFF SET HEADING OFF SELECT trim(runid_seq.nextval) FROM dual; EXIT EOA echo `cat runid_val.sql` V_RUNID=`sqlplus -s $uid/$password@$database @runid_val.sql`... (5 Replies)
Discussion started by: vj_76
5 Replies

2. Shell Programming and Scripting

Trim white spaces using awk

Hi, I have a CSV file with footer information as below. The third value is the number of records in the file. Sometimes it contains both leading and trailing white spaces which i want to trim using awk. C,FOOTER , 00000642 C,FOOTER , 00000707 C, FOOTER,... (2 Replies)
Discussion started by: mona
2 Replies

3. Shell Programming and Scripting

stripping white space...

Hi All; Having a problem with a file.. the file contains the following data... (a snapshot) 1331F9E9DB7C2BB80EAEDE3A8F043B94,AL7 1DZ,M,50 186FDF93E1303DBA217279EC3671EA91,NG5 1JU,M,24 3783FFAF602015056A8CD21104B1AAAF,CH42 4NQ,M,17 It has 3 columns sepreated by a , the second column... (7 Replies)
Discussion started by: Zak
7 Replies

4. UNIX for Dummies Questions & Answers

SED with White Space

Dear Members, Suppose i have a variable test which stores a string as below: test='John drives+++++++++a+++++car' now i want to use sed on the above variable and replace + with a white space, so that i get echo $test should give me 'john drives a car' Between... (1 Reply)
Discussion started by: sandeep_1105
1 Replies

5. Shell Programming and Scripting

sed + white space

Hi, What sed command (if sed is the right command) can remove ALL white space from my file. I have a csv, except I want to remove all white space between commas and characters. My idea (without testing) sed 's/ //g' Is there a better way? (18 Replies)
Discussion started by: mcclunyboy
18 Replies

6. UNIX for Dummies Questions & Answers

filename with white space

our user creates a text file with a white space on the filename. this same file is transfered to unix via automation tool. i have a korn shell script that reads these files on a input directory and connects to oracle database to run the oracle procedures which will load the data from each of the... (2 Replies)
Discussion started by: wtolentino
2 Replies

7. Shell Programming and Scripting

awk - trim white space from a field / variable

Hi, Consider the data (FS = |): 1| England |end 2| New Zealand |end 3|Australia|end 4| Some Made Up Country |end 5| West Indies|end I want the output to be (i.e. without the leading and trailing white space from $2) England New Zealand Australia Some Made Up Country West... (4 Replies)
Discussion started by: Storms
4 Replies

8. Shell Programming and Scripting

Add white space

hi guys how can i add spacein file name with sed if strings have no space around dash input 19-20 ( 18-19 ) ABC-EFG output after add white space 19 - 20 (18 - 19 ) ABC - EFG thx in advance (2 Replies)
Discussion started by: mhs
2 Replies

9. Shell Programming and Scripting

Putting white Space at the end of the string

Hi Guys, Hope, you all are doing good out there. I am writing a shell script and currrint in need of your help. This is what I need to do; I have position based plain file. One of the fields is 15 character long. I need to fill that field. The problem is that the value is dynamic, it could... (4 Replies)
Discussion started by: singh.chandan18
4 Replies

10. Shell Programming and Scripting

Trim Space

In Shell, I have output of a unix command as test1 test2015 but I want it as test1 test2015 can anyone help me out. Use code tags, thanks. (3 Replies)
Discussion started by: OscarS
3 Replies
STRCAT(3)						   BSD Library Functions Manual 						 STRCAT(3)

NAME
strcat, strncat -- concatenate strings LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <string.h> char * strcat(char * restrict s, const char * restrict append); char * strncat(char * restrict s, const char * restrict append, size_t count); DESCRIPTION
The strcat() and strncat() functions append a copy of the nul-terminated string append to the end of the nul-terminated string s, then add a terminating ''. The string s must have sufficient space to hold the result. The strncat() function appends not more than count characters where space for the terminating '' should not be included in count. RETURN VALUES
The strcat() and strncat() functions return the pointer s. EXAMPLES
The following appends ``abc'' to ``chararray'': char *letters = "abcdefghi"; (void)strncat(chararray, letters, 3); The following example shows how to use strncat() safely in conjunction with strncpy(3). char buf[BUFSIZ]; char *input, *suffix; (void)strncpy(buf, input, sizeof(buf) - 1); buf[sizeof(buf) - 1] = ''; (void)strncat(buf, suffix, sizeof(buf) - 1 - strlen(buf)); The above will copy as many characters from ``input'' to ``buf'' as will fit. It then appends as many characters from suffix as will fit (or none if there is no space). For operations like this, the strlcpy(3) and strlcat(3) functions are a better choice, as shown below. (void)strlcpy(buf, input, sizeof(buf)); (void)strlcat(buf, suffix, sizeof(buf)); SEE ALSO
bcopy(3), memccpy(3), memcpy(3), memmove(3), strcpy(3), strlcat(3), strlcpy(3) STANDARDS
The strcat() and strncat() functions conform to ISO/IEC 9899:1999 (``ISO C99''). BSD
August 11, 2002 BSD
All times are GMT -4. The time now is 11:46 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy