Unit 8

Arithmetic Operators (additional to Chapter 7)

DIV (Gives the whole number after the first number is divided by the second, i.e. it ignores the fractional part)

E.g. DIV (10,2) gives 5 and DIV(11,9) gives 1

MOD(Gives the remainder after the first number is divided by the second, i.e. it ignores the fractional part)

E.g. DIV (10,2) gives 0 and DIV(11,9) gives 2

String Manipulation

LENGTH(string)

LENGTH(“hi”) would return 2

LENGTH(0123) would return 4

SUBSTRING (String, start character, number of characters)

SUBSTRING (“HELLO”, 0, 1) will return “H”.

SUBSTRING (“GOODBYE”,4,3) will return “BYE”.

UPPER(string) and LOWER(string)

UPPER (“hello”) will return “HELLO”.

LOWER (“HELLO”) will return “hello”.

Library Routines

ROUND (It takes a real value and limits how many numbers there are after the decimal point)

E.g. ROUND(10.123,1) gives 10.1 and ROUND(4.8293,2) gives 4.82

RANDOM (This generates a random number between two values that it takes as parameter)

E.g. RANDOM(10,20) will return any number between 10 and 20

File Handling

• Reading from a file (Stages)

  • Open the file using its filename (filename is a string value)

  • Read the data value and do something with it (output/store)

  • Close the file

• Syntax

OPEN filename

Variable identifier = READ (filename)

CLOSE filename

• Example

OPEN “data.txt”

OUTPUT (READ(“data.txt”))

CLOSE “data.txt”

• Writing to a file (Stages)

  • Open the file using its filename (filename is a string value)

  • Write the data to the file

  • Close the file

• Syntax

OPEN filename

WRITE data

CLOSE filename

• Example

OPEN “colour.txt”

WRITE “red”

CLOSE “colour.txt”