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Problems from string to int array

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Join Date: Sep 2007

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BigFormat

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Problems from string to int array

Sep 7th, 2007

Hi guys, I've got troubles with a conversion.
My function:
void stringFormat (char *input, int nums)
receives a string like this:
"name;3,45,5,6,77;"
and a number indicating how many numbers in the String (in this case 5)
I've got to tokenize the string in order to obtain:
1) a string named data: "name"
2) an array of int made of the numbers received: numbers[0]=3; numbers[1]=45; and so on 'til 77
Here's my wrong solution:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
void stringFormat(char *input, int nums){
 
	char *data;
	int *numbers[nums];
	int i=0;		
	char *p;
 
	p = strtok (input,";");
	if(p != NULL) data=p;
 
	p = strtok (NULL, ",;");
  	while (p != NULL)
  	{
  	  numbers[i] = p;
	  i++; 
	  p = strtok (NULL, ",;");
 	}
 
	i=0;
 
        /* I check array content  */
	while (i<(nums)){
		printf("%d\n", *(numbers[i]) );
		i++;
	}
}
void stringFormat(char *input, int nums){
	
	char *data;
	int *numbers[nums];
	int i=0;		
	char *p;
	
	p = strtok (input,";");
	if(p != NULL) data=p;
	
	p = strtok (NULL, ",;");
  	while (p != NULL)
  	{
  	  numbers[i] = p;
	  i++; 
	  p = strtok (NULL, ",;");
 	}
	
	i=0;

        /* I check array content  */
	while (i<(nums)){
		printf("%d\n", *(numbers[i]) );
		i++;
	}
}

...any suggestion will be highly appreciated !!

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Join Date: Aug 2005

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iamthwee

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Re: Problems from string to int array

Sep 7th, 2007

>int *numbers[nums];

Doesn't that have to be like... a static value? It may be ok I dunno, If you wanna do that dynamically maybe you need malloc or something? Or you could just initialise it to be a really big value, but that's not cast iron...

Last edited by iamthwee; Sep 7th, 2007 at 3:52 pm.

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Aia

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Re: Problems from string to int array

Sep 7th, 2007

•

Originally Posted by BigFormat

Hi guys, I've got troubles with a conversion.

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
     int *numbers[nums];  /* this is an array of pointers of type int */
 
    char *p; /* this is a pointer to a string */
 
     numbers[i] = p; /* You are trying to assign a string to an element of the array of pointers type int */
     int *numbers[nums];  /* this is an array of pointers of type int */
      
    char *p; /* this is a pointer to a string */
    
     numbers[i] = p; /* You are trying to assign a string to an element of the array of pointers type int */

That doesn't work. You need to convert the number value store in the string pointed by `p' into integer before storing in numbers[i].
Maybe use sscanf() to read the value from the string.

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iamthwee

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Re: Problems from string to int array

Sep 8th, 2007

•

Originally Posted by iamthwee

>int *numbers[nums];

Doesn't that have to be like... a static value? It may be ok I dunno, If you wanna do that dynamically maybe you need malloc or something? Or you could just initialise it to be a really big value, but that's not cast iron...

Um actually that may be wrong...I could have sworn I remembered something like that not working...lolz

Help with Code Tags

(Toggle Plain Text)

#include <stdio.h>
#include <string.h>
 
void stringFormat ( int nums );
 
int main ( void )
{
  stringFormat ( 143 ); /*test*/
  getchar();
  return 0;
}
void stringFormat ( int nums )
{
  int numbers[nums];
  int i;
  for ( i = 0; i < nums; i++ )
  {
    numbers[i] = 1;
    printf ( "%d", numbers[i] );
  }
}

Anyway, have a look at some daniweb tutorials which you should find useful.

http://www.daniweb.com/code/coder5020-timestamp-2.html
http://www.daniweb.com/tutorials/tutorial45806.html

Last edited by iamthwee; Sep 8th, 2007 at 4:42 am.

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BigFormat

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Re: Problems from string to int array

Sep 8th, 2007

•

Originally Posted by iamthwee

Um actually that may be wrong...I could have sworn I remembered something like that not working...lolz
Help with Code Tags

C Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
void stringFormat ( int nums );
 (...)
#include <stdio.h> #include <string.h> void stringFormat ( int nums ); (...)

Your code works correctly on my PC, maybe assigning a variable instead of a static value it's only bad style since I get "only" a gcc warning.
Anyway, even if I iniitialise it with a big value the problem persists.

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BigFormat

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Re: Problems from string to int array

Sep 8th, 2007

•

Originally Posted by Aia

Help with Code Tags

c Syntax (Toggle Plain Text)
     int *numbers[nums];  /* this is an array of pointers of type int */
 
    char *p; /* this is a pointer to a string */
 
     numbers[i] = p; /* You are trying to assign a string to an element of the array of pointers type int */
int *numbers[nums]; /* this is an array of pointers of type int */ char *p; /* this is a pointer to a string */ numbers[i] = p; /* You are trying to assign a string to an element of the array of pointers type int */
That doesn't work. You need to convert the number value store in the string pointed by `p' into integer before storing in numbers[i].
Maybe use sscanf() to read the value from the string.

You guessed the core of the problem.
I've seen some sscanf() tutorials but I've not understood the difference with strtok().
In my case, there's no way to perform a "on the fly" conversion using i.e. atoi()
something like:
numbers[i] = atoi(p);
dunno why it doesn't work!
ps: my variable numbers it's a pointer to an array of int, maybe I missed a couple of parenteses so it looked like an array of pointers of type int..

Last edited by BigFormat; Sep 8th, 2007 at 5:47 am.

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iamthwee

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Re: Problems from string to int array

Sep 8th, 2007

Did you look at those links?

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Re: Problems from string to int array

Sep 8th, 2007

•

Originally Posted by iamthwee

Did you look at those links?

Yes I read something and put the rest in bookmarks, but I've not found my answer.
I'd like to know why my code doesn't work with strtok() and atoi(), before changing everything and using sscanf() (which I found a little tricky..)

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iamthwee

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Re: Problems from string to int array

Sep 8th, 2007

No idea, I don't have a compiler to test so this is from my head.

It doesn't put it into an array but that's should be trivial. Maybe it will give you hints?

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
 
#include <stdio.h>
#include <string.h>
int main ()
{
  char str[] ="retard;3,4510,-5,6,77;";
  char * pch;
  printf ("Splitting: %s",str);
  printf("\n");
  pch = strtok (str,",;");
 
  int count = 0;
  char data[BUFSIZ];
  while (pch != NULL)
  {
     char buf[BUFSIZ];
     char *p;
     printf ("%s ",pch);
 
    int i = strtol(pch, &p, 10);
 
    if (pch[0] != '\n' && (*p == '\n' || *p == '\0'))
    {
      printf (" = Valid integer %d entered\n", i);
      /*Add this to your integer array*/
    }
    else
    {
      printf(" = This is string not an integer\n");
      strcpy(data,pch);
    }
 
     pch = strtok (NULL, ",;");
     count++;  
  }
 
  printf("The string named Data is \"%s\" ",data);
 
  getchar();
  return 0;
}
 
#include <stdio.h>
#include <string.h>
int main ()
{
  char str[] ="retard;3,4510,-5,6,77;";
  char * pch;
  printf ("Splitting: %s",str);
  printf("\n");
  pch = strtok (str,",;");
 
  int count = 0;
  char data[BUFSIZ];
  while (pch != NULL)
  {
     char buf[BUFSIZ];
     char *p;
     printf ("%s ",pch);
 
    int i = strtol(pch, &p, 10);
 
    if (pch[0] != '\n' && (*p == '\n' || *p == '\0'))
    {
      printf (" = Valid integer %d entered\n", i);
      /*Add this to your integer array*/
    }
    else
    {
      printf(" = This is string not an integer\n");
      strcpy(data,pch);
    }
 
     pch = strtok (NULL, ",;");
     count++;  
  }
 
  printf("The string named Data is \"%s\" ",data);
 
  getchar();
  return 0;
}

Last edited by iamthwee; Sep 8th, 2007 at 7:12 am.

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Aia

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Re: Problems from string to int array

#10

Sep 8th, 2007

•

Originally Posted by BigFormat

You guessed the core of the problem.
I've seen some sscanf() tutorials but I've not understood the difference with strtok().
In my case, there's no way to perform a "on the fly" conversion using i.e. atoi()
something like:
numbers[i] = atoi(p);
dunno why it doesn't work!
ps: my variable numbers it's a pointer to an array of int, maybe I missed a couple of parenteses so it looked like an array of pointers of type int..

Here's the changes for your code to work using sscanf() to read the integer.

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
    int numbers[nums]; /* this needs to be an array of integers */
    .
    .
    .
     while (p != NULL)
     {
        sscanf(p, "%d", &numbers[i]); /* scan string for an integer */
        ++i; 
        p = strtok (NULL, ",;");
     }
    int numbers[nums]; /* this needs to be an array of integers */
    .
    .
    .
     while (p != NULL)
     {
        sscanf(p, "%d", &numbers[i]); /* scan string for an integer */
        ++i; 
        p = strtok (NULL, ",;");
     }

•

Originally Posted by BigFormat

numbers[i] = atoi(p);
dunno why it doesn't work!

You need to make numbers[i] an array of integers and not an array of pointers of type int. Right now you are trying to assign whatever atoi(p) gives you to a pointer memory which it can only hold the address of another memory and not an integer value.

Last edited by Aia; Sep 8th, 2007 at 9:57 pm.