Thread: How to access value allocated by malloc

My code is not working as it supposed to do. I want a program that allocates memory for three integer's, then I want to assign value at each memory location, then I want to print value stoared at each location's

Code:

 #include<stdio.h>

#include<stdlib.h>


int main ()
{
  int i;
  int *ptr;
  ptr = malloc( 2 * sizeof(*ptr));	
  if( ptr != NULL )                      /*Check for failure. */
     {
        *ptr = 0;
         ptr++;	
        *ptr = 1;
         ptr++;	
        *ptr = 2;
         ptr++;	


	    for ( i = 0; i < 2; i++)
		{
			printf("%d \n", *ptr);
		    ptr++;
		}		 
	 }
	 
  free( ptr );                           /*Release memory. */


  return 0;
}

I don't get output as I want.

When I compile code I get this output

234918894
7274542

...allocates memory for three integer's

Code:

ptr = malloc( 2 * sizeof(*ptr));

Your code and your intention don't match.
Don't you see the problem ?

ptr++; This looses the address of the original pointer.

Originally Posted by thmm

Code:

ptr = malloc( 2 * sizeof(*ptr));

Your code and your intention don't match.
Don't you see the problem ?

ptr++; This looses the address of the original pointer.

I get correct value without loop

Code:

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

int main ()
{
  int i;
  int *ptr;
  ptr = malloc( 3 * sizeof(*ptr));    
  if( ptr != NULL )                      /*Check for failure. */
     {
         *ptr = 0;
         printf("%d \n", *ptr);
         printf("%p \n", ptr);
         ptr++;
        *ptr = 1;
         printf("%d \n", *ptr);
         printf("%p \n", ptr);
         ptr++;
        *ptr = 2;
         printf("%d \n", *ptr);
         printf("%p \n", ptr);                    
     }
       
  free( ptr );                           /*Release memory. */


  return 0;
}

0
00730D48
1
00730D4C
2
00730D50

I don't know what's wrong with "for" loop in previous program.

Originally Posted by Salem

> ptr++;
Just stop doing this.
Do NOT muck about with the pointer you use to store the result of malloc - ever!

I want to verify whether the dynamic memory is allocated for three integer by malloc and it store value at allocated location

I understand program allocated space for three integer variables

Code:

#include<stdio.h>
 #include<stdlib.h>
  
int main ()
{
  int i;
  int *ptr;
 
  ptr = malloc( 3 * sizeof(*ptr));  
  if( ptr != NULL )                     
  {
       
  }
     
  free( ptr );
 
  return 0;
}

I want to print allocated dyanamic memory for three integer variables. I want to store values 10, 13 and 19 in allocated memory for three integer variables

I don't understand how to print allocated memory address and how to store values 10, 13 and 19 in allocated memory for three integer variables