Pointer in C

Pointer in c

#include <stdio.h>

int main()
{
    int j;
    int i;
    int *p; // declare pointer

    i = 7;
    p = &i; // The pointer now holds the address of i
    j = *p;

    printf("i = %d \n", i);  // value of i
    printf("j = %d \n", j);  // value of j
    printf("*p = %d \n", p); // the address held by the pointer

    *p = 32; // asigns value to i via the pointer

    printf("i = %d \n", i);   // value of i
    printf("j = %d \n", j);   // value of j
    printf("*p = %d \n", p);  // the address held by the pointer
    printf("&i = %d \n", &i); // address of i
  
  	return 0;
    }

Pointers c

#include <stdio.h>
int main()
{
   int *p;
   int var = 10;

   p= &var;

   printf("Value of variable var is: %d", var);
   printf("\nValue of variable var is: %d", *p);
   printf("\nAddress of variable var is: %p", &var);
   printf("\nAddress of variable var is: %p", p);
   printf("\nAddress of pointer p is: %p", &p);
   return 0;
}
#output
#Value of variable var is: 10
#Value of variable var is: 10
#Address of variable var is: 0x7fff5ed98c4c
#Address of variable var is: 0x7fff5ed98c4c
#Address of pointer p is: 0x7fff5ed98c50

Pointer c

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

int main()
{
    int *ptr, i , n1, n2;
    printf("Enter size: ");
    scanf("%d", &n1);

    ptr = (int*) malloc(n1 * sizeof(int));

    printf("Addresses of previously allocated memory: ");
    for(i = 0; i < n1; ++i)
         printf("%u\n",ptr + i);

    printf("\nEnter the new size: ");
    scanf("%d", &n2);

    // rellocating the memory
    ptr = realloc(ptr, n2 * sizeof(int));

    printf("Addresses of newly allocated memory: ");
    for(i = 0; i < n2; ++i)
         printf("%u\n", ptr + i);
  
    free(ptr);

    return 0;
}

Source: programiz.com

Pointer in C

#include <stdio.h>
int main()
{
   int* pc, c;
   
   c = 22;
   printf("Address of c: %p\n", &c);
   printf("Value of c: %d\n\n", c);  // 22
   
   pc = &c;
   printf("Address of pointer pc: %p\n", pc);
   printf("Content of pointer pc: %d\n\n", *pc); // 22
   
   c = 11;
   printf("Address of pointer pc: %p\n", pc);
   printf("Content of pointer pc: %d\n\n", *pc); // 11
   
   *pc = 2;
   printf("Address of c: %p\n", &c);
   printf("Value of c: %d\n\n", c); // 2
   return 0;
}

Function pointer in c

// Basic syntax
ret_type (*fun_ptr)(arg_type1, arg_type2,..., arg_typen);

// Example
void fun(int a)
{
    printf("Value of a is %d\n", a);
}

// fun_ptr is a pointer to function fun() 
void (*fun_ptr)(int) = &fun;

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