Question

How do you pass parameters by reference using pointers?

Answer 1

In C, you can pass parameters by reference using pointers. By passing a pointer to a variable, you allow a function to directly access and modify the original variable. Here's how you can pass parameters by reference using pointers:

1. Declare a function that takes a pointer parameter:

   void modifyValue(int *ptr) {
       // Function logic goes here
   }
    

2. Inside the function, you can dereference the pointer to access and modify the original variable:

   void modifyValue(int *ptr) {
       *ptr = 42;  // Modifying the value of the variable pointed by 'ptr'
   }
    

   Here, the value of the variable pointed to by ptr will be changed to 42.

3. When calling the function, pass the address of the variable as the argument:

   int num = 0;
   modifyValue(&num);  // Pass the address of 'num' to the function
    

   The function modifyValue will receive the memory address of num through the pointer parameter ptr. Consequently, any modifications made to *ptr inside the function will directly affect the original variable num.

After the function call, the value of num will be 42 because it was modified inside the modifyValue function using the passed pointer.

Passing parameters by reference using pointers is useful when you want to modify variables within a function and have those changes reflected in the original variables outside the function.