strtok() a phone number

This is a discussion on strtok() a phone number within the C Programming forums, part of the General Programming Boards category; What i gotta do: Write a program that inputs a tele phone #as astring in the form (555)555-5555. The program ...

  1. #1
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    strtok() a phone number

    What i gotta do:

    Write a program that inputs a tele phone #as astring in the form (555)555-5555. The program should use function strok() to extract the area code as a token , the first three digits of the phone # as a token and the last four as a token. the seven digits of the phone should be concatenated into one string.The program should convert the are-code string to int and convert the phone # string to long. both the area-code and the phone #should be printed

    Output:
    Code:
    Enter a phone number in the form (555) 555-5555:
    (555)555-5555
    
    The integer area code is 555
    The long integer phone number is 555555
    press any key to continue...
    What i got sofar:
    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main()
    {
    	char string[ 10 ];
    	char *tokenPtr;
    
    	printf( "Enter a phone number in the form (555) 555-5555: \n" );
    	scanf( "%s", string);
    
    	tokenPtr = strtok( string, "() -" );
    
    	while ( tokenPtr != NULL ){
    			printf( "\nThe integer area code is %s\n", tokenPtr );
    			tokenPtr = strtok( NULL, "() -" );
    		}
    
    
    
    	return 0;
    
    }
    its only a bit of it i dont know how to set it up with gets, stoi(), strcopy(), and strcat()
    Last edited by Sure; 06-27-2005 at 07:14 PM.

  2. #2
    Code Goddess Prelude's Avatar
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    9,796
    >scanf( "%s", string);
    Let's do the math, k? string is 10 characters long, but you require the format of (assuming no internal whitespace) (xxx)xxx-xxxx, which is 13 characters. Add the null character at the end and it's 14, at the very least. Since you don't use a field width modifier for %s, scanf will happily read until whitespace is encountered, so (once again assuming no internal whitespace), you're looking at a guaranteed buffer overflow. How would you describe that call to scanf as anything but an assured failure?

    >while ( tokenPtr != NULL ){
    There's really no need for a loop. Since this clearly isn't meant to be a rock solid program, you can just assume that the number is formatted properly and go about your business:
    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main ( void )
    {
      char buffer[BUFSIZ];
      char area[4] = {0};
      char number[9] = {0};
      char *p;
    
      printf ( "Enter a phone number (ex. (555) 555-5555): " );
      gets ( buffer ); /* I weep as I type this */
    
      p = strtok ( buffer, "()- " );
    
      if ( p != NULL )
        strncat ( area, p, sizeof area - 1 );
    
      p = strtok ( NULL, "()- " );
    
      if ( p != NULL )
        strncat ( number, p, sizeof number - 1 );
    
      p = strtok ( NULL, "()- " );
    
      if ( p != NULL )
        strncat ( number, p, sizeof number - 1 );
    
      puts ( area );
      puts ( number );
    }
    Converting the area code to an integer and the number to a long is pretty simple, but rather than do your homework for you, I'll leave it to you and a good reference to figure out. Here's one piece of advice though: don't use atoi, if there's an error during conversion then you'll invoke undefined behavior. The only way to avoid that is to thoroughly validate your input beforehand. strtol is a much better option.
    My best code is written with the delete key.

  3. #3
    Registered User
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    k thx bro ....

  4. #4
    Code Goddess Prelude's Avatar
    Join Date
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    Posts
    9,796
    >k thx bro ....
    My best code is written with the delete key.

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