Visual Basic 2005 Guide
Performing Calculations


Computers are good at performing calculations. Remember that the operators, + - * / are used for arithmetic in Visual Basic programs. There are a number of built-in functions to carry out useful bits of Maths. For a full list, explore the MSDN (help) that comes with Visual Basic. Some of the most useful are listed below,

Math.Abs(x)The number x without its sign
Math.Ceiling(x)Rounds x up to the nearest integer
Math.Floor(x)Rounds x down to the nearest integer
Math.Max(x, y)The largest of the values x and y
Math.Min(x, y)The smallest of the values x and y
Math.Pow(x, p)Raises x to the power p
Math.Round(x, d)Rounds the number x to d decimal places
Math.Sqrt(x)The square root of x

Programming Tasks

  1. Write a program into which the user can enter the two shorter sides of a right-angled triangle. Use Pythagoras' Theorem to find the length of the longest side.
  2. A temperature in degrees Celsius can be converted to degrees Fahrenheit using the formula F = (9/5) * C + 32. Write a program that allows the user to input a temperature in Celsius and output the equivalent in degrees Fahrenheit.

Random Numbers

Computers cannot generate actual random numbers. The term pseudorandom is used to reflect the fact that the numbers appear random.

In order to ensure that the 'random' numbers are not predictable in a program, we use the RANDOMIZE function at the beginning of the program. Random numbers are generated from a seed value. The randomize function changes the seed value for random numbers based on the current value of the computer's clock.

The rnd() function returns a random number less than 1 and greater than 0. To get a random integer between a and b where a is the smaller of the two numbers, you write,

intRandom = CInt(Int((b - a + 1) * Rnd() + a))

So, to get a random integer between 1 and 100, you would write,

intRandom = CInt(Int((100 * Rnd()) + 1))

Another Programming Task

  1. Write a program that simulates the rolling of two dice.