Just a tiny little problem...

Hi,

THis is a program which alphabetizes a list of strings using bubblesort. But theres only one compile error: variable-sized may not be initialized. BUt it's already been initialized. Pls help, other than this the problem worked fine.

THnx

Code:

#include <stdio.h>
#include <string.h>

void bubbleSort_strings( char *a[], int size );

int main()
{
   int i, size = 4;
   char *strings[ size ] = { "ABC", "BCD", "CDE", "DEF" };

   bubbleSort_strings( strings, size );

   printf( "Sorted list of strings are: \n" );
   for ( i = 0; i < size; i++ )
      printf( "%s ", strings[ i ] );

   system( "PAUSE" );
   return 0;
}


void bubbleSort_strings( char *a[], int size )
{
   int pass, j;
   char hold[ 100 ];

   for ( pass = 1; pass <= size - 1; pass++ )
      for ( j = 0; j <= size - 2; j++ )
         if ( strcmp( a[ j ], a[ j + 1 ] ) == 1 ) {
            strcpy( hold, a[ j ] );
            strcpy( a[ j ], a[ j + 1 ] );
            strcpy( a[ j + 1 ], hold );
         }
}

>>> int i, size = 4;

const int size = 4;
int i;

Where is system() declared? (And you might want to look in the FAQ sometime to see some reasons why system() is a bad idea!)

changed to const, but still with the same compile error. Why ?

why system() is a bad idea? I checked the FAQ but couldn't find this topic?

pls help

thnx

http://www.cprogramming.com/boardfaq.html#execs

any fix for my little problem of my program? Like the compile error ?

Originally posted by Nutshell
any fix for my little problem of my program? Like the compile error ?

Yes, listen to adrian and declare the size as a const variable.

Also if you must use system() include <stdlib.h>

thing is, i already declared it with 'const', still didn't work, same error!

pls help

thnx

Code:

#include <stdio.h>
#include <string.h>
#define SIZE 4
void bubbleSort_strings( char *a[], int size );

int main()
{
   int i;
   char *strings[ SIZE ] = { "ABC", "BCD", "CDE", "DEF" };

   bubbleSort_strings( strings, SIZE );

   printf( "Sorted list of strings are: \n" );
   for ( i = 0; i < SIZE; i++ )
      printf( "%s ", strings[ i ] );

   //system( "PAUSE" );
   return 0;
}


void bubbleSort_strings( char *a[], int size )
{
   int pass, j;
   char hold[ 100 ];

   for ( pass = 1; pass <= size - 1; pass++ )
      for ( j = 0; j <= size - 2; j++ )
         if ( strcmp( a[ j ], a[ j + 1 ] ) == 1 ) {
            strcpy( hold, a[ j ] );
            strcpy( a[ j ], a[ j + 1 ] );
            strcpy( a[ j + 1 ], hold );
         }
}

Hmm..maybe const is different in C as compared to C++ (which I compile in)

Try a #define as above

Code:

#include <stdio.h>
#include <string.h>

void bubbleSort_strings( char *a[], int size );

int main()
{
   const int size = 4;
   int i;
   char *strings[ size ] = { "ABC", "BCD", "CDE", "DEF" };

   bubbleSort_strings( strings, size );

   printf( "Sorted list of strings are: \n" );
   for ( i = 0; i < size; i++ )
      printf( "%s ", strings[ i ] );

  // system( "PAUSE" );
   return 0;
}


void bubbleSort_strings( char *a[], int size )
{
   int pass, j;
   char hold[ 100 ];

   for ( pass = 1; pass <= size - 1; pass++ )
      for ( j = 0; j <= size - 2; j++ )
         if ( strcmp( a[ j ], a[ j + 1 ] ) == 1 ) {
            strcpy( hold, a[ j ] );
            strcpy( a[ j ], a[ j + 1 ] );
            strcpy( a[ j + 1 ], hold );
         }
}

This compiles and runs for me. (I have commented out your pause, my compiler does not need it). The program does, however, still have problems. Your 4 strings are currently in order, try replacing "ABC" with "XYZ" and see what happens!

Hi Fordy, yes, possibly, I am running this through VC++! Anyway, he will need a compile time resolvable value, #define would definitely be resolvable!

*** EDIT ***

My house "C" person seemed to think that const would work for "C" as well.

NutShell: What compiler/OS are you using?

Originally posted by adrianxw
Hi Fordy, yes, possibly, I am running this through VC++! Anyway, he will need a compile time resolvable value, #define would definitely be resolvable!

*** EDIT ***

My house "C" person seemed to think that const would work for "C" as well.

NutShell: What compiler/OS are you using?

Hmm...weird inconsistancies......

I compiled this as a Cpp file in DevC++ and it worked with the const...I wondered if it would be different with a C file...didnt bother to find out..

I can understand the compiler being dubious about using a varible for this, but as C++ promotes the use of const for constants instead of #define I automatically assumed C would do the same....perhaps not

NUTSHELL:

Anyway, if you are declaring the contents of the array, you dont need to specify the size of the array.....The compiler will do it for you

If the size can be changed at runtime, you need to use malloc and create the memory space on the freestore

Yeah...tried it in C

Code:

const int size = 4;
   char *strings[ size] = { "ABC", "BCD", "CDE", "DEF" };

This is AOK in C++, but the compiler chokes if you compile it as a C file..........

Seems const is not resolved at compile time as it is in C++.......

I guess it was altered in C++ to help do away with #define

I'm sure some C-Fullblood will give the answer to this soon

Intruiging huh! Have you tried changing one of his strings?

>>>
Your 4 strings are currently in order, try replacing "ABC" with "XYZ" and see what happens!
<<<

VC++ did not like that at all!

changed my code to below, still have problems...

Code:

#include <stdio.h>
#include <string.h>

void bubbleSort_strings( char *a[], int size );

int main()
{
   int i;
   const int size = 4;
   char *strings[ ] = { "XYE", "BCD", "CDE", "DEF" };

   bubbleSort_strings( strings, size );

   printf( "Sorted list of strings are: \n" );
   for ( i = 0; i < size; i++ )
      printf( "%s ", strings[ i ] );

   system( "PAUSE" );
   return 0;
}


void bubbleSort_strings( char *a[], int size )
{
   int pass, j;
   char hold[ 100 ];

   for ( pass = 1; pass <= size - 1; pass++ )
      for ( j = 0; j <= size - 2; j++ )
         if ( strcmp( a[ j ], a[ j + 1 ] ) > 0 ) {
            strcpy( hold, a[ j ] );
            strcpy( a[ j ], a[ j + 1 ] );
            strcpy( a[ j + 1 ], hold );
         }
}

>char *strings[ ] = { "XYE", "BCD", "CDE", "DEF" };
Okay so far, but there's a bug right here that will creep up on you later.

>strcpy( a[ j ], a[ j + 1 ] );
BANG! You're dead, another victim to the access violation bug. You can't assign to a string constant, char *strings[] has the same access rules as char *strings in this case.

enjoy.

-Prelude