## Expression building for Unit conversion

Building of expressions can be done for different units using different divisors.

## Learning Objectives

- Making simple formulas.
- Reuse of left hand side variable for recalculation with new units in a formula.

## Source Code

`class ExpUnitConversion`

{

public static void main(String[] args)

{

double d,t,s;

d=1200;t=400;

s=d/t;

System.out.println("Speed (in m/s) = "+s);

s=(d/1000)/(t/3600);

System.out.println("Speed (in km/hr) = "+s);

}

}

## Run Output

## Code Understanding

** double d,t,s;** //Three double variables declared

**d=1200;t=400;**

**d** assigned **1200** which is distance in meters and **t** assigned **400** which is time in seconds

**s=d/t;**

This formula will thus give speed in m/s in variable **s** based on values filled in **d** and **t** variable.

**System.out.println(“Speed (in m/s) = “+s);**

Speed in m/s will be printed

**s=(d/1000)/(t/3600);**

Since the s above has already been printed for value in m/s we can again build a new formula for km/hr speed and fill its value in s. For km/hr formula we simply divide meter value in d with 1000 as 1 km=1000 m and t with 3600 as 1 hour = 3600 seconds. For this division we do it in separate brackets so that precedence of operator rules are properly followed.

System.out.println(“Speed (in km/hr) = “+s);

** System.out.println(“Speed (in km/hr) = “+s);**

With this we print the speed in km/hr as the s will now contain value based on recalculation based on new formula.

## Notes

- Reuse of variables should normally be done only when it is being used for similar purposes.
- Reuse of variables may be avoided if the use of variables is required for displaying all values together.

**Suggested Filename(s): **ExpUnitConversion.java

sunmitra| Created: 5-Mar-2018 | Updated: 5-Mar-2018|