What is the Difference Between Call by Value and Call by Reference?

The main difference between call by value and call by reference lies in how the function parameters are passed and how changes made to the parameters within the function affect the original variables. Here are the key differences:

• Call by Value:
• A copy of the variable is passed to the function.
• The actual arguments and passed parameters of a function refer to different memory locations.
• Changes made inside the function do not affect the original variables.
• Suitable for simple data types (int, float, etc.).
• Reduces the risk of unintentional side effects.
• Call by Reference:
• The variable itself is passed to the function, with the address of the variable being copied.
• The actual arguments and passed parameters of a function refer to the same memory location.
• Changes made inside the function affect the original variables.
• Suitable for complex data types (arrays, objects, etc.).
• Increases the risk of unintentional side effects.

In summary, call by value copies a variable's value, while call by reference passes a pointer to the variable. Depending on the desired output, developers need to decide which method to use. Call by value is the default method in programming languages like C++, PHP, Visual Basic NET, and C#, whereas call by reference is supported only in Java language.

Comparative Table: Call by Value vs Call by Reference

Here is a table comparing the differences between call by value and call by reference:

In summary, the main differences between call by value and call by reference are:

• In call by value, a copy of the parameter's value is passed to the method, and changes made inside the method have no effect on the original value outside the method.
• In call by reference, a reference to the actual parameter is passed to the method, and changes made inside the method are reflected in the actual parameters of the caller.
• Call by value is generally preferred when you want to prevent any unintended changes to the original value, while call by reference is used when you want to modify the original value.

Note that the choice between call by value and call by reference depends on the specific requirements and understanding the difference between the two is important for making the right decision.