Returning an Array of Pointers

Code examples of manipulating an array of pointers.


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

#define MAXLIST 10

struct ipList
{
	int id;
	char *name;
	char *ip;
};

struct ipList **getList( void );
void printList( struct ipList **list );

int main( void )
{ 
	struct ipList **theList;

	theList = getList( );
	printList( theList );

	return 0;
}

struct ipList **getList( void )
{
	struct ipList **list;
	int i;
	
	list = malloc( MAXLIST * sizeof( struct ipList * ) );
	i = 0;
	while ( i < MAXLIST )
	{
		list[ i ] = malloc( sizeof( struct ipList ) );
		list[ i ]->id = i;
		list[ i ]->name = "citibank.co.cx";
		list[ i ]->ip = "209.249.147.15";
		i++;
	}

	return ( list );
}

void printList( struct ipList **list )
{
	int i = 0;
	
	while ( i < MAXLIST )
	{
		printf( "%s - %s", ( list[ i ]->name ), ( list[ i ]->ip ) );
		i++;
	}
}

we can change the function getList slightly:


struct ipList **getList( void )
{
	static struct ipList *list[ MAXLIST ];
	int i;
	
	//list = malloc( MAXLIST * sizeof( struct ipList * ) );
	i = 0;
	while ( i < MAXLIST )
	{
		list[ i ] = malloc( sizeof( struct ipList ) );
		list[ i ]->id = i;
		list[ i ]->name = "citibank.co.cx";
		list[ i ]->ip = "209.249.147.15";
		i++;
	}

	return ( list );
}

or we could have the main array created in main like this:


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

#define MAXLIST 10

struct ipList
{
	int id;
	char name[ 35 ];
	char ip[ 15 ];
};

void getList( struct ipList *list[ ] );
struct ipList *makeIP( void );
void printList( struct ipList *list[ ] );

int main( void )
{ 
	struct ipList *theList[ MAXLIST ];
	
	getList( theList );


	printList( theList );

	return 0;
}

void getList( struct ipList *list[ ] )
{
	int i = 0;
	
	while ( i < MAXLIST )
	{
		list[ i ] = makeIP( );
		list[ i ]->id = i;
		strcpy( ( list[ i ]->name ), "citibank.co.cx" );
		strcpy( ( list[ i ]->ip ), "209.249.147.15" );
		i++;
	}
}

struct ipList *makeIP( void )
{
	struct ipList *temp;
	temp = malloc( sizeof( struct ipList ) );
	return ( temp );
}


void printList( struct ipList *list[ ] )
{
	int i = 0;
	
	while ( i < MAXLIST )
	{
		printf( "%s - %s", ( list[ i ]->name ), ( list[ i ]->ip ) );
		i++;
	}
}

2010: 1
2009: 12 11 8 5
2008: 12 5 4 3 2 1
2007: 12 11 10 9 8 7 6 5 4 3 2 1
2006: 12 11 10 9 8 7 6 5 4 3 2 1
2005: 12 11 10 8 7 6 5 3 2 1
2004: 11 10 9 7 6 5 4 3 2 1

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