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:

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#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;
}

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I don't get output as I want.

When I compile code I get this output

234918894
7274542

Quote:

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...allocates memory for three integer's

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Code:

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

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

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

Quote:

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Originally Posted by thmm

Code:

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

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

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

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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;
}

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0
00730D48
1
00730D4C
2
00730D50

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

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

Code:

---

  ptr = malloc( 3 * sizeof(*ptr)); 
  if( ptr != NULL )                      /*Check for failure. */
  {
    for ( i = 0; i < 2; i++)
    {
      ptr[i] = i;
    }

    for ( i = 0; i < 2; i++)
    {
      printf("%d \n", ptr[i]);
    }       
  }
     
  free( ptr );

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If you want it in pointer notation, make a copy of the pointer.

Code:

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  ptr = malloc( 3 * sizeof(*ptr)); 
  if( ptr != NULL )                      /*Check for failure. */
  {
    int *temp = ptr;
    for ( i = 0; i < 2; i++)
    {
      *temp++ = i;
    }

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

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Quote:

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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!

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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:

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

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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

> I want to verify whether the dynamic memory is allocated for three integer by malloc and it store value at allocated location
Well if malloc returns a non-null pointer, then you have your memory.

Code:

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

int main(int argc, char **argv)
{
  int asize = 3;
  int *ptr = malloc(asize * sizeof(*ptr));
  if (ptr != NULL) {            /*Check for failure. */
    int *temp = ptr;
    int base = 10;
    for (int i = 0; i < asize; i++) {
      base += i * 3;
      printf("Storing the value %d at memory location %p\n", base, (void *)temp);
      *temp++ = base;
    }

    temp = ptr;
    for (int i = 0; i < asize; i++) {
      printf("the value at memory location %p is %d\n", (void *)temp, *temp);
      temp++;
    }
  }
  free(ptr);
  return 0;
}

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