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Aug 19th, 2008

problem with strtok()

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Hi All,

I am facing a problem with using the function strtok(). Following is just a sample code.
The code below stores the string str delimited by comma into an array.

I want to modify the code below so that array would contain an empty space/new line if a value is missing.

i.e., if str[] = source, desti, string1,,string3 ; then my array should hold an empty space/ new line in place of string2.

Can somebody help me with this?
Thanks in Advance

c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <conio.h>
#include <string.h>
 
main() 
{
	char str[] = "source,desti,string1,string2,string3";
	char delims[] = ",";
	char *result = NULL;
	char myArray[10][50],*p;
 
 
	result = strtok( str, delims );
 
	while( result != NULL ) 
	{
		printf( "%s \n", result );
		result = strtok( NULL, delims );
	}
 
       getch();
 
}
#include <stdio.h>
#include <conio.h>
#include <string.h>

main() 
{
	char str[] = "source,desti,string1,string2,string3";
	char delims[] = ",";
	char *result = NULL;
	char myArray[10][50],*p;

	
	result = strtok( str, delims );
	
	while( result != NULL ) 
	{
		printf( "%s \n", result );
		result = strtok( NULL, delims );
	}
	
       getch();

}

Last edited by Ancient Dragon; Aug 19th, 2008 at 2:34 pm. Reason: add code tags

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smnadig

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Aug 19th, 2008

Re: problem with strtok()

Maybe you could find the length of the string inbetween the commas. If it is zero then fill it with a space or newline.

iamthwee

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Aug 19th, 2008

Re: problem with strtok()

strtok ignores empty fields. Edward would recommend using another solution, like strcspn and some method of reading or copying a substring:

c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
int main()
{
  const char *str = "source,desti,string1,,string3";
  const char *delims = ",";
 
  size_t start = 0;
 
  while (str[start] != '\0') {
    size_t end = strcspn(str + start, delims);
 
    printf("%.*s\n", end, str + start);
 
    start += (str[start + end] != '\0') ? end + 1 : end;
  }
}
#include <stdio.h>
#include <string.h>

int main()
{
  const char *str = "source,desti,string1,,string3";
  const char *delims = ",";

  size_t start = 0;

  while (str[start] != '\0') {
    size_t end = strcspn(str + start, delims);

    printf("%.*s\n", end, str + start);

    start += (str[start + end] != '\0') ? end + 1 : end;
  }
}

The benefit of this approach is that you don't modify the original string anymore, so it works with string literals.

Radical Edward

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Aug 20th, 2008

Re: problem with strtok()

Click to Expand / Collapse Quote originally posted by Radical Edward ...

strtok ignores empty fields. Edward would recommend using another solution, like strcspn and some method of reading or copying a substring:
c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
int main()
{
  const char *str = "source,desti,string1,,string3";
  const char *delims = ",";
 
  size_t start = 0;
 
  while (str[start] != '\0') {
    size_t end = strcspn(str + start, delims);
 
    printf("%.*s\n", end, str + start);
 
    start += (str[start + end] != '\0') ? end + 1 : end;
  }
}
#include <stdio.h> #include <string.h> int main() { const char *str = "source,desti,string1,,string3"; const char *delims = ","; size_t start = 0; while (str[start] != '\0') { size_t end = strcspn(str + start, delims); printf("%.*s\n", end, str + start); start += (str[start + end] != '\0') ? end + 1 : end; } }
The benefit of this approach is that you don't modify the original string anymore, so it works with string literals.

Thanks a lot

It was very helpful

smnadig

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Nov 24th, 2009

Re: problem with strtok()

Hi guys, I'm new to C here. How do I assign the value to a variable printed from the line:

C Syntax (Toggle Plain Text)
printf("%.*s\n", end, str + start);
printf("%.*s\n", end, str + start);

Please advise, thanks!

ABuNeNe

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