dynamic memory allocation for single variable

I want to allocate dynamic memory for a single variable and in that variable I want to store a value 5

What should my codes be for this

Code:

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#include<stdio.h>
#include<stdlib.h> 


int main ()
{
  int *a = (int*) malloc (1 * sizeof(int)); // memory is allocated for varaible a
 
  return 0;
}

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What should my codes be for this

Code:

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#include<stdio.h>
#include<stdlib.h> 
 
int main ()
{
  int *a = malloc(sizeof(*a)); // memory is allocated for varaible a
  if (a != NULL) { // if the memory was successfully allocated
      *a = 5;  // assign 5 to the "memory location" that a points to
      printf("a is %d\n", *a);
      free(a);    // free the allocated memory
  }
 
  return 0;
}

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Quote:

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Originally Posted by Hodor

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Code:

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*a = 5;  // assign 5 to the "memory location" that a points to

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Why should we use this sign * because we have already used it * when we were allocating memory for variable

The asterisk '*' is used for two different places and purposes.

Code:

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int *a = NULL;

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is used to create a pointer variable called a, initialized to NULL.

Code:

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a = malloc(sizeof(*a));

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This allocates memory on the heap and assigns it to the pointer variable, a.

Code:

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*a = 5;

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Assigns the value 5 to the memory area allocated on the heap and pointed to by a. The asterisk in this statement "dereferences" the pointer before assigning the data.

a, along with most variable names, should be replaced with a more useful name that represents the use. "count", or something else.

We usually don't allocate memory for one variable except as part of learning about pointers.

You need to study a good book on the C Programming Language, and not some short tutorial, or podcast, online.

Quote:

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Originally Posted by Player777

Code:

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*a = 5;  // assign 5 to the "memory location" that a points to

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Why should we use this sign * because we have already used it * when we were allocating memory for variable

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There is a difference between DECLARING a variable and USING it:

Code:

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int *a; // declare 'a' as a pointer to an int
a = malloc( sizeof( int ) ); // assign an address of a dynamically allocated block of memory to 'a'.
*a = 5; // The * here is the indirection operator (access to the address inside 'a').

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