The Difference Between Call by Value and Call by Reference
When we’re coding or programming, we need to take into consideration the different types of parameters that we use. Two of the most commonly used parameters are call by value and call by reference. Understanding the differences between the two is essential in creating a functional and efficient code.
What is Call by Value?
Call by value is a parameter passing method where a copy of the parameter’s value is passed to the function. This means that the original value of the parameter is not modified. Any changes made to the parameter within the function only exist within that function and do not apply to the original value.
Consider this example:
“`
function square(x) {
x = x * x;
return x;
}
let num = 5;
square(num);
console.log(num); // Output: 5
“`
In the above code, the value of `num` remains unchanged even after passing it to the `square` function.
What is Call by Reference?
Call by reference is a parameter passing method where the memory address or reference of the parameter is passed to the function. Any changes made to the parameter within the function directly affect the original value of the parameter outside of the function.
Consider this example:
“`
function changeName(obj) {
obj.name = “Sarah”;
}
let person = { name: “John” };
changeName(person);
console.log(person); // Output: { name: “Sarah” }
“`
In the above code, the value of `person` is modified within the `changeName` function, applying the changes to the original object outside of the function.
The Benefits and Drawbacks of each Parameter Passing Method
Call by value is advantageous when dealing with primitive data types such as numbers and strings. It ensures that the original value of the parameter remains unchanged and reduces the likelihood of unintentional modifications. However, it is not recommended when dealing with larger objects as it creates a copy of the object in memory, causing performance issues.
Call by reference is useful when dealing with complex data types such as arrays and objects as it allows for modifications to the original value of the parameter. However, it requires careful consideration to avoid unintended modifications and potential side effects.
In conclusion, understanding the differences between call by value and call by reference is an essential aspect of programming. Choosing the appropriate parameter passing method depending on the situation can significantly impact the efficiency and functionality of your code.
Table difference between call by value and call by reference
| Call by Value | Call by Reference |
|---|---|
| Passes a copy of the actual parameter’s value to the function | Passes the memory address of the actual parameter to the function |
| Changes made to the parameter inside the function does not affect the original value | Changes made to the parameter inside the function affects the original value |
| Typically used for simple data types like integers, characters and floats | Typically used for complex data types like arrays, structures and objects |
| Requires less memory as only the value is copied | Requires more memory as the memory address is passed |
| Call by value is generally faster as no extra memory is allocated | Call by reference can be slower due to extra memory allocation and dereferencing |