The CONST definition CONST Pi = 3.14159, City = ‘New York’; Constant identifiers are used when you do not want the value of an identifier to change why not just put the value in the program? Note: The compiler automatically defines the type to the constant identifier by looking at the value assigned to it.

Reserved words Certain words have special meaning to the compiler. Therefore these words cannot be used as constant or variable identifiers. We have seen some examples: DIV, MOD VAR, CONST PROGRAM, BEGIN, END

String Variables Note: This is not part of the Pascal standard. It was added to Turbo Pascal (and some other Pascal compilers) To declare a string variable we could write: VAR Country: string[13]; To assign a value to a string variable we could write: Country := ‘United States’;

More about integers What if you need an integer larger than 32767? Using integer type would be incorrect another type called LongInt is used -2147483648 -> 2147483647 other integer types are: byte (0->255) shortint (-128->127) word (0->65535)

More about reals Reals also have other types real 6 bytes 11 to 12 digits single 4 bytes 7 to 8 digits double 8 bytes 15 to 16 digits extended 10 bytes 19 to 20 digits

Chapter 3 topics write / writeln readln VAR declaration CONST definition assignment statement (including arithmetic)

Homework #3 Problem #1 Write a program that asks the user for his or her age and place of birth. Then write both pieces of information back to the screen in a single WriteLn statement (using a CONST string). Hint: What kind of data type would you want to use for someone's age? What kind of data type would you want to use for a geographic location?

Homework # 3 (con’t) Problem #2 Problem #14 on Page 99 of your text: Write a program to calculate the product of any five real numbers read. What difficulty would the program encounter if it calculated the product of five integers?

Instructions for handing in homework Mail to grader at: fd202@omicron.nyu.edu each program should be included as an attachment The answer to #14, part 2 should be contained in the message body.