C++ unit conversion

create a unit conversion  calculator which will calculate three different units, length, volume and mass/weight. We will first ask the  user what unit they want to convert, then we will ask what unit they are converting f rom, then we will do  the appropriate conversion.

At least 4 functions.

At least one function needs to demonstrate a single loop 

At least one function needs to demonstrate a nested loop

At least one function needs to demonstrate the use of a multi-alternative IF structure or SWITCH statement

At least one function needs to demonstrate the proper usage of an array 

One function needs to contain program input (e.g. cin) 

One function needs to output something to the screen and to a file

I/O to/from the console 

Comments that convince the instructor you understand the code you wrote