Difference Between Pass by Value and Pass by Reference

Professionals write codes to direct a computer or application to carry out certain tasks as part of the computer programming process. Each programming language provides functions, which are a collection of instructions or statements that, when called, carry out a certain purpose.

These command sets accept inputs or a few arguments in exchange for return outputs. You can pass these arguments by value or by reference. Programming requires a clear understanding of the differences between references and pass-by values.

So what differentiates pass by value from pass by reference? When a parameter value is copied to another variable, this is known as pass by value. Pass by reference, on the other hand, involves passing the function’s real parameter.

Professionals can manage and maintain software programs or applications due to these programming statements. 

What Is Pass by Value?

A process known as “pass by value” copies the value of a function parameter to another memory address. Within the function, changing a variable only affects the copy.

The original value will not be impacted by these alterations or changes. newValue refers to the copied value in a new memory location. On the newValue rather than the original value, it is claimed that the adjustments were made.

Pass by value is demonstrated in the example below:

let a = 100;let b = a;a = 90;

console.log(a); // prints 90

console.log(b); // prints 100

Since distinct memory is assigned to it upon assignment, changing the value of “a” has no effect on the value of “b.”

What Is Pass by Reference?

In a pass by reference mechanism, the function receives the memory address. The original variable will be made available to the function.

The memory address changes with the real variable when it is passed to the function. Since there is no copying problem, the procedure uses less memory and takes less time.

Here is an example of a pass-by reference:

let a = {‘name’ : ‘Rohan’, ‘age’ : 30};

let b = a;

a.name = ‘Sam’;

console.log(a); // prints {‘name’ : ‘Sam’, ‘age’ : 30}

console.log(b); // prints {‘name’ : ‘Sam’, ‘age’ : 30}

Since the variables “a” and “b” both refer to the same object, any changes to “a’ value will also update “b” and vice versa.

Key Difference between Pass by Value and Reference

  • Copying the value of a function argument to another variable is known as “passing by value.” Passing actual parameters to a function is what is meant by pass by reference.
  • Changes to the pass by value made within the function are not reflected in the starting value. Any modifications made inside the pass by reference function are mirrored in the initial value.
  • Passing a parameter by value creates a copy of the actual parameter, but passing a parameter by reference gives the function the address of the original parameter.
  • While pass by reference functions retrieve the original content of the variable, pass by value functions obtain a duplicate of the actual content.
  • Since pass by value includes copying values, more RAM is needed. Pass by reference, on the other hand, uses less memory because there is no copying involved.
  • Passing data by value takes longer than passing data by reference because values must be copied.

Similarities between Pass by Value and Reference

  • They both work with programming languages.
  • For designing effective and efficient programs, both are ideal.
  • Both improve the programs’ ability to be maintained and managed.
  • These are two different ways of calling a function.


What, therefore, is the difference between pass by reference and pass by value in C? The latter is a mechanism for sending the real parameter to the function, whilst the former is a means of shifting the value of the function parameter to another variable.

Changes to the pass by value made within the function do not affect the actual value. This occurs because the process copies the original parameters, which uses up more memory and time.

Changes made inside the function using pass by reference are mirrored in the initial value. This occurs because the function receives the address of the real parameter, which uses less time and memory.

It’s essential to comprehend the distinction between pass by value and pass by reference using an example. It will assist you in overcoming difficulties brought on by pass by reference and pass by value in Python.