Kotlin Program to Convert Celsius to Fahrenheit

You can convert Celsius to Fahrenheit in Kotlin using the formula fahrenheit = celsius * 9 / 5 + 32. For example: val fahrenheit = celsius * 9 / 5 + 32.

Examples

Input0

Output32.0

Input25

Output77.0

Input-40

Output-40.0

How to Think About It

To convert Celsius to Fahrenheit, multiply the Celsius value by 9, then divide by 5, and finally add 32. This formula changes the temperature scale from Celsius to Fahrenheit.

Algorithm

1

Get the temperature value in Celsius.

2

Multiply the Celsius value by 9.

3

Divide the result by 5.

4

Add 32 to the result.

5

Return or print the Fahrenheit value.

Code

kotlin

fun main() {
    val celsius = 25.0
    val fahrenheit = celsius * 9 / 5 + 32
    println("$celsius Celsius is equal to $fahrenheit Fahrenheit")
}

Output

25.0 Celsius is equal to 77.0 Fahrenheit

Dry Run

Let's trace the example where Celsius is 25.0 through the code.

1

Initialize Celsius

celsius = 25.0

2

Multiply by 9

25.0 * 9 = 225.0

3

Divide by 5

225.0 / 5 = 45.0

4

Add 32

45.0 + 32 = 77.0

5

Print result

"25.0 Celsius is equal to 77.0 Fahrenheit"

Step	Calculation	Result
Multiply by 9	25.0 * 9	225.0
Divide by 5	225.0 / 5	45.0
Add 32	45.0 + 32	77.0

Why This Works

Step 1: Multiply Celsius by 9

Multiplying by 9 scales the Celsius temperature to the Fahrenheit scale proportionally.

Step 2: Divide by 5

Dividing by 5 adjusts the scale difference between Celsius and Fahrenheit degrees.

Step 3: Add 32

Adding 32 shifts the zero point from Celsius to Fahrenheit, aligning freezing points.

Alternative Approaches

Using a function

kotlin

fun celsiusToFahrenheit(celsius: Double): Double {
    return celsius * 9 / 5 + 32
}

fun main() {
    val tempC = 0.0
    println("$tempC Celsius is ${celsiusToFahrenheit(tempC)} Fahrenheit")
}

This approach improves code reuse by wrapping the conversion in a function.

Reading input from user

kotlin

fun main() {
    print("Enter temperature in Celsius: ")
    val celsius = readLine()!!.toDouble()
    val fahrenheit = celsius * 9 / 5 + 32
    println("$celsius Celsius is equal to $fahrenheit Fahrenheit")
}

This approach allows dynamic input from the user instead of hardcoded values.

Complexity: O(1) time, O(1) space

Time Complexity

The calculation uses a fixed number of arithmetic operations, so it runs in constant time.

Space Complexity

Only a few variables are used, so the space needed is constant.

Which Approach is Fastest?

All approaches run in constant time; using a function adds clarity but no significant overhead.

Approach	Time	Space	Best For
Direct calculation	O(1)	O(1)	Simple quick conversion
Function	O(1)	O(1)	Reusable code
User input	O(1)	O(1)	Interactive programs