swap 2 pointers

pointer-swap.c

@@ -0,0 +1,72 @@
+/**
+ * @file function_call-by-reference.c
+ * @author kunal jain ([email protected])
+ * @brief Program to swap 2 pointers
+ * @version 0.1
+ * @date 2022-02-02
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ */
+
+#include<stdio.h>
+
+// Function to swap 2 pointers
+// int** address_of_pa -> Address of first pointer variable.
+// int** address_of_pb -> Address of second pointer variable.
+void swap (int** address_of_pa, int** address_of_pb) {
+    // address_of_p where p is an int pointer (int*) must be of type (int*)*
+    // address of an int pointer must be of type int**
+
+    // temporary variable to store value at address_of_pa
+    // and set same value at address_of_pb
+    int* temp;
+
+    // swap two pointers as any other variable.
+    temp = *address_of_pa;
+    *address_of_pa = *address_of_pb;
+    *address_of_pb = temp;
+
+    // pa and pb is swapped after this.
+    // Can be verified using print statements in main function.
+}
+
+int main(void) {
+    // Declare 2 integers in this program. Then create
+    // 2 pointer variables that point to the 2 integers.
+    // The aim of the program is to swap the 2 pointers.
+
+    int a = 7, b = 5;
+
+    // pa is a pointer pointing to a
+    // pb is a pointer pointing to b
+    int* pa = &a;
+    int* pb = &b;
+
+    printf("Value at pointer pa -> %d\n", *pa);
+    printf("Value of pointer pa -> %d\n", pa);
+    printf("Address of pointer pa -> %d\n\n", &pa);
+
+    printf("Value at pointer pb -> %d\n", *pb);
+    printf("Value of pointer pb -> %d\n", pb);
+    printf("Address of pointer pb -> %d\n", &pb);
+
+    // Pass address instead of pointer variable.
+
+    // &pa -> address of pa
+    // &pb -> address of pb 
+    swap(&pa, &pb);
+
+
+    printf("\nAfter swap:\n");
+
+    printf("Value at pointer pa -> %d\n", *pa);
+    printf("Value of pointer pa -> %d\n", pa);
+    printf("Address of pointer pa -> %d\n\n", &pa);
+
+    printf("Value at pointer pb -> %d\n", *pb);
+    printf("Value of pointer pb -> %d\n", pb);
+    printf("Address of pointer pb -> %d\n", &pb);
+
+    return 0; 
+}