What is the difference between 'call by value' and 'call by reference'?

What is the difference between 'call by value' and 'call by reference'?

• A. Call by value passes a pointer; call by reference passes a copy
• B. Call by value passes a copy of the variable; call by reference passes the variable's address
• C. Call by value is faster than call by reference
• D. Call by value modifies the original variable; call by reference does not

Answer: (B)

The distinction between 'call by value' and 'call by reference' is rooted in how function parameters are handled during a function call. When using 'call by value,' a copy of the actual variable is made and passed to the function. This means that any changes made to that parameter within the function do not affect the original variable outside that function; it only modifies the copy. Therefore, 'call by value' ensures that the integrity of the original data remains intact. In contrast, 'call by reference' passes the address of the variable instead of its value. This allows the function to operate directly on the original variable, enabling any alterations made within the function to affect the variable outside of it. Because the function has access to the original variable, changes are reflected immediately. This clear separation in behavior helps programmers understand how data is manipulated within their functions and informs choices regarding which method to use based on the requirements of their program.

The distinction between 'call by value' and 'call by reference' is rooted in how function parameters are handled during a function call. When using 'call by value,' a copy of the actual variable is made and passed to the function. This means that any changes made to that parameter within the function do not affect the original variable outside that function; it only modifies the copy. Therefore, 'call by value' ensures that the integrity of the original data remains intact.

In contrast, 'call by reference' passes the address of the variable instead of its value. This allows the function to operate directly on the original variable, enabling any alterations made within the function to affect the variable outside of it. Because the function has access to the original variable, changes are reflected immediately.

This clear separation in behavior helps programmers understand how data is manipulated within their functions and informs choices regarding which method to use based on the requirements of their program.