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Finding an InString Method for C

Posted on 2011-03-08
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Last Modified: 2012-05-11
Hi,

I need an inString function that returns a 0 or 1 to use in my IF statements. I do not think the attached code is correct, and I would love it if I could tap someone's brain to get a working solution.

I searched on here already and could not find anything.

I would like to make this so that I can search for any sized string in the first string.

Thanks
static int inString(const char* testvalue, char token[1])
{
	// variables
	int i;
	// resolve token in string
	for (i = 0; i < strlen(testvalue); i++)
		if (testvalue[i] == token)
			return 1;
	// return
	return 0;
}

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Question by:dilithiumtoys_dot_com
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7 Comments
 
LVL 33

Expert Comment

by:phoffric
ID: 35075153
I think you probably are looking for one of these two library functions:
    http://www.cplusplus.com/reference/clibrary/cstring/strchr/

    http://www.cplusplus.com/reference/clibrary/cstring/strstr/
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Author Comment

by:dilithiumtoys_dot_com
ID: 35078188
Neither function seems to be working for me. Specifically I need to find if a character exists in the string and get a Boolean/testable value from it. How do I test either to determine if the character is actually in the string?



 
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Expert Comment

by:Subrat (C++ windows/Linux)
ID: 35080298
strchr() can do your job. I don't know how it's not working for you.

Have a look on the below code

#include "stdio.h"
#include "string.h"

int inString(const char* testvalue, char token) {
  const char* retval = strchr(testvalue, token);
  if(retval == NULL)
    return 0;
  else
    return 1;
}

int main() {
  int res = inString("Subrat", 's');
  printf(res?"Charecter present\n":"Char not present\n");
  res = inString("Subrat",'S');
  printf(res?"Charecter present\n":"Charecter not present\n");
  return 0;
}
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LVL 33

Expert Comment

by:phoffric
ID: 35082179
>> Neither function seems to be working for me. Specifically I need to find if a character exists in the string and get a Boolean/testable value from it.

If you post the code that does not work for you, then we can help fix it. As this problem is a typical academic assignment, I was unable to provide you with code. But, if you want to learn how to find the problem yourself, just post your code for our advice.
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LVL 33

Expert Comment

by:phoffric
ID: 35082196
Did you copy the code in the strchr link and try to make it fit for your program? Here is the sample code:
/* strchr example */
#include <stdio.h>
#include <string.h>

int main ()
{
  char str[] = "This is a sample string";
  char * pch;
  printf ("Looking for the 's' character in \"%s\"...\n",str);
  pch=strchr(str,'s');
  while (pch!=NULL)
  {
    printf ("found at %d\n",pch-str+1);
    pch=strchr(pch+1,'s');
  }
  return 0;
}

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Author Comment

by:dilithiumtoys_dot_com
ID: 35084440
Hi,

I am using SubRat2009's example in the attached code, but with strstr(). I am passing in

str1 = "eula.txt"
str2 = "."

I am getting the integer 0 as a result, when I should be getting 1 back. Whats wrong?

Thanks
static int inString(const char* str1, const char* str2)
{
	// variables
	const char* retval; 
	// check string length
	if (strlen(str1) == 0 || strlen(str2) == 0)	
		return 0;
	// resolve string
	retval = strstr(str1, str2);
	// return the result
	if(retval == NULL)
		return 0;
	else
		return 1;
}

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Accepted Solution

by:
Subrat (C++ windows/Linux) earned 2000 total points
ID: 35088606
Nothing wrong here. Can you post the main() function where u r calling this function.
Below is the tested code and working fine with returing 1.

int _tmain(int argc, _TCHAR* argv[])
{
      char* str1 = "eula.txt";
    char* str2 = ".";
      int x = inString(str1, str2);
      printf("%d\n",x);

      return 0;
}
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