Declaring a table with unknown size (C)

[Transmit]

Hi everyone,

I need to declare an array of chars but I don't know how big it will be from the start of the program.

example:
Someone gives me a name:
John
Array gets filled with john
[j][o][h][n]

so the size of this array is 4 chars (not more)!

how can I declare an array that way?
I tried: char tablename[] but that doesn't seem to work.

Thanks in advance!!

[willakawill]

Hi everyone,

I need to declare an array of chars but I don't know how big it will be from the start of the program.

example:
Someone gives me a name:
John
Array gets filled with john
[j][o][h][n]

so the size of this array is 4 chars (not more)!

how can I declare an array that way?
I tried: char tablename[] but that doesn't seem to work.

Thanks in advance!!

Hi. To size an array dynamically you need to use the 'new' and 'delete' keywords:

char *ar;
//your code here
ar = new char[sizeofstring + 1];
//your code here
delete [] ar;

[drhowarddrfine]

"new" and "delete" are not valid in C. So you need to malloc to create space for the array but others more experienced than I can show you how.

[willakawill]

"new" and "delete" are not valid in C. So you need to malloc to create space for the array but others more experienced than I can show you how.

Oops. My mistake.

/* MALLOC.C: This program allocates memory with
 * malloc, then frees the memory with free.
 */

#include <stdlib.h>         /* For _MAX_PATH definition */
#include <stdio.h>
#include <malloc.h>

void main( void )
{
   char *string;

   /* Allocate space for a path name */
   string = malloc( _MAX_PATH );
   if( string == NULL )
      printf( "Insufficient memory available\n" );
   else
   {
      printf( "Memory space allocated for path name\n" );
      free( string );
      printf( "Memory freed\n" );
   }
}