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Section 3.6

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Functions - terminology

- Functions arecalled from within a procedure.
- e.g., Sqr(x) is a function call

- A function receives 1 or more input values & returns auniqueoutput value
n = Left (string, 3)

Output assigned to n

Function name

input

Numeric functions

- Sqr
- Int
- Round
- Rnd

Numeric functions - Sqr

- Sqr (n) : returns the square root of n.
- requires exactly one positive numeric input value
- may contain an expression for n

- Examples: assumen = 25
Sqr (16) returns 4

Sqr (2) returns 1.414214

Sqr (n) returns 5

Sqr (n + 11) returns 6

Sqr (-4) returns an error

Numeric functions - Int

- Int (n) returns the greatest integer less than or equal to n
- requires exactly one integer input value
- n may be a numeric expression

- Examples: assume n is 10
Int (5.2) returns 5

Int (-6.7) returns -7

Int (n + 15) returns 25

Numeric functions - Round

- How numbers are rounded to integers:
- 23.7 rounds up to 24
- 23.4 rounds down to 23
- 23.5 rounds up to 24
nRound (n)

1.3 1

1.7 2

-1.6-2

.2 0

Another format for Round

- Round (2.357, 2) returns 2.36
- Round (1234.97899, 2) returns 1234.98
- This variation of Round is useful when our programs are processing monetary values.
- Example:
Private Sub Command1_Click()

Picture1.Print Round(txtNum.Text, 2)

End Sub

Two mathematical operators that are useful in programs

- If x & y are integers, then the integer quotient of x divided by y can be found by using \
quotient = x \ y

- Also, to get the remainder, use mod:
remainder = x mod y

- try it with: x = 26; y = 7

Numeric functions - Rnd

- Used to enable your program to generate pseudorandom values; useful in the creation of games.
- Rnd does not require any input value and returns a numeric value r where 0 <= r < 1

Int (Rnd * 10)will generate

a value that is between 0 & 9

Some uses of Rnd

- Randomly generate an integer between 1 & 10:
x = 1 + Int(10 * Rnd)

- Randomly generate a 0 or 1:
x = Int (2 * Rnd)

- Randomly generate evens between 0 & 98:
x = 2 * Int (50 * Rnd)

more...

More uses of Rnd

- Randomly generate
- a lowercase alphabetic character
- an uppercase alphabetic character
- the uppercase alphabetic characters between A & J

Still more examples of Rnd

- Randomly generate an integer between
- 1 & 10
- 3 & 23
- 0 & 100 evens only
- 5 & 75 divisible by 5

- Randomly generate
- a lowercase alphabetic character
- an uppercase alphabetic character
- p. 132: #116, 117

Lab

- Page 132 # 121
- Page 133 #122, 124