Thread: pointers & malloc test code

Hello list ...

I think I'm grokking it - but please critique the following code and comments therein:

Code:

/*
program to demonstrate the use of pointers and
malloc to dynamically allocate memory.

Remember these rules:
1.  Always assign an address to a pointer before using it!
2.  Conversely, never assign a value to *some_ptr without first
     assigning an address to some_ptr!
*/

#include <stdio.h>
#include <malloc.h>

//insert function prototypes below

int main( void )
{
    int  *ptr2_int;

ptr2_int = (int *) malloc(sizeof(int));

/* Breakdown of the above line:
sizeof(int) => returns the number of bytes that a variable
                 of type "int" requires.
malloc(some_number) => grabs "some_number" of consecutive
                                 bytes of the available (unused) memory
                                 on the target machine. Returns the starting
                                 address of those bytes.
(int *) => This is "type casting". It says that the starting address
             of the available memory will be a pointer to data that will be
             of type "int".

In short:

"allocate from RAM enough space for a variable of type "int". Then assign
the starting address of that memory to ptr2_int, which is a pointer to data
of type "int"
*/

*ptr2_int = 999;

    printf ("content of ptr2_int: %p\n", ptr2_int);
    printf ("value pointed to by ptr2_int: %d\n", *ptr2_int);
    return 0;
}

Much obliged!
--
Duke

@Salem
Your reply here might just have answered my question about using Turbo C (and it's manuals) in another thread

Funny thing though - the code compiles under Linux (gcc) with no warnings or errors. I set up Code::Blocks to use -Wall.
Regardless, I appreciate your comments, and will update my code.
--
Duke

Originally Posted by dukester

@Salem
Your reply here might just have answered my question about using Turbo C (and it's manuals) in another thread

Funny thing though - the code compiles under Linux (gcc) with no warnings or errors. I set up Code::Blocks to use -Wall.
Regardless, I appreciate your comments, and will update my code.
--
Duke

Duke... please see my message in the other thread... Code::Blocks with MinGW is an ok package if you are doing both C and C++ work and don't need windows resource editors... otherwise...

Saw you comments regarding Pelles C -- thanks!
--
Duke