“Call by value” and “call by reference” are two different mechanisms used to pass arguments to functions in programming languages. Here are five key differences between them:
Data Passing:
Call by Value: In call by value, a copy of the actual value (or the content of the variable) is passed to the function. Any modifications made to the parameter inside the function do not affect the original variable.
Call by Reference: In call by reference, the memory address (reference) of the actual variable is passed to the function. This means that changes made to the parameter inside the function affect the original variable.
Effect on Original Data:
Call by Value: Changes made to the parameter inside the function do not affect the original data outside the function. The function works with a local copy of the variable.
Call by Reference: Changes made to the parameter inside the function directly affect the original data outside the function. The function works with the actual variable in memory.
Memory Usage:
Call by Value: Requires more memory as it involves copying the values. Each function call has its own set of variables.
Call by Reference: Generally uses less memory because it operates on the actual variables, and there is no need to create copies.
Syntax:
Call by Value: Arguments are passed by value, and the function receives a copy of the value. Syntax is straightforward and commonly used in languages like C and Java.
Call by Reference: Arguments are passed by reference, and the function receives the memory address of the variable. Syntax often involves pointers or references and is common in languages like C++.
Use Cases:
Call by Value: Suitable for simple data types or situations where the original data should not be modified by the function. It provides data encapsulation and helps prevent unintended side effects.
Call by Reference: Useful when the function needs to modify the original data or when working with large data structures to avoid the overhead of copying large amounts of data.
Understanding the distinction between call by value and call by reference is crucial for programming, as it affects how data is manipulated within functions and how changes made inside a function impact the broader program.