The swapping process refers to changing the value from one variable to another variable. In this article, we will be learning about swapping 2 variables with Various Approaches.
We would be using various ways to swap variables:
- Using 3rd variable.
- Without using 3rd variable.
- With the destructing assignment.
Approach 1: Using 3rd variable: Here we create a temporary variable that will hold the value of one of the variables to perform the operation.
- Let’s say we create a temp variable that stores the value of a variable A.
- Then we copy the value of B to A (A would be overwritten).
- Then we copy the value of temp to B (earlier value of A).
Syntax:
temp = a; a = b; b = temp;
Note: Here, temp is the new 3rd variable that we are using to swap the value of variables a and b.
Example:
HTML
<script> var a = 20; var b = 10; var temp; console.log(`before swapping: a= ${a}`); console.log(`before swapping b= ${b}`); temp = a; a = b; b = temp; console.log(`after swapping a= ${a}`); console.log(`after swapping b= ${b}`);</script> |
Output:
before swapping: a= 20 before swapping b= 10 after swapping a= 10 after swapping b= 20
Approach 2: Without using 3rd variable: Here we would be using an arithmetic operation to swap 2 values.
- Firstly, we add a + b to a (a would be greater than b as it is).
- Now we subtract b from a so the value of b is now available to b
- Now we subtract a with b again to a so a will have the value of B
Syntax:
a = a + b; b = a - b; a = a - b;
Example:
HTML
<script> var a=10; var b=20; console.log(`before swap a= ${a}`); console.log(`before swap a= ${b}`); a=a+b;//10=10+20 now a would be 30 b=a-b;//20=30-10 now b would be 10 a=a-b;//30=30-10 so a would be now 20 console.log(`after swap a= ${a}`); console.log(`after swap a= ${b}`);</script> |
Output:
before swap a= 10 before swap a= 20 after swap a= 20 after swap a= 10
Approach 3: With destructing Assignment: Here we will be using destructing Assignment.
The destructing assignment makes it possible to unpack values from an array or object or from other properties into distinct variables.
Syntax:
[b,a]=[a,b];
Example:
HTML
<script> var a=40; var b=30; console.log(`before swap a= ${a}`); console.log(`before swap a= ${b}`); // a would be swapped to b and b would be swapped to a [b,a]=[a,b]; console.log(`after swap a= ${a}`); console.log(`after swap a= ${b}`);</script> |
Output:
before swap a= 40 before swap a= 30 after swap a= 30 after swap a= 40
Note: When a large amount of data is concerned Destructing Assignment may helpful.
Where to use which method?
- If the operation is related to a numeric value you can swap values with the arithmetic operation(2nd method).
- If the operation is related to other types like string or boolean you can use the 1st method.
