# Scala program to swap two numbers

Scala | Swapping two numbers: Here, we are going to learn how to swap two numbers in Scala programming language?
Submitted by Shivang Yadav, on April 21, 2020

Given two numbers, we have to swap them.

Example:

```    Input:
a = 10
b = 20

Output:
a = 20
b = 10
```

## 1) Swapping two numbers using third variable

To swap two values, there is a simple approach is using a temporary variable that stores the element for swapping.

Algorithm:

Let, variable a contains first value, variable b contains second value and temp is the temporary variable.

```    Step 1: temp = a
Step 2: a = b
Step 3: b = temp
```

Program:

```object myObject {
def main(args: Array[String]) {
var a = 10
var b = 20

println("Values before swapping:\t a= " + a + ", b= " + b)

// swapping
var temp = a
a = b
b = temp

println("Values after swapping:\t a= " + a + ", b= " + b)

}
}
```

Output

```Values before swapping:	 a= 10, b= 20
Values after swapping:	 a= 20, b= 10
```

### 2) Swapping two numbers without using third variable

We can also swap two numbers without using the third variable. This method saves computation space hence is more effective.

Let, variable a contains first value, variable b contains second value.

```    Step 1: a = a + b
Step 2: a = a - b
Step 3: b = a - b
```

Program:

```object myObject {
def main(args: Array[String]) {
var a = 10
var b = 20

println("Values before swapping:\t a= " + a + ", b= " + b)

// swapping
a = a + b
b = a - b
a = a - b

println("Values after swapping:\t a= " + a + ", b= " + b)

}
}
```

Output

```Values before swapping:	 a= 10, b= 20
Values after swapping:	 a= 20, b= 10
```

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