{ Programmer : E. Adams

Course : CS 430/CS 530

Date Due : September 22, 2005

Language : Pascal

Compiler : Free Pascal

Source Filename : Homework4.pp

Executable Filename: Homework4.exe

Professor : E. Adams

}

{ Purpose: To write a brief Pascal progrm that obtains 3 numbers from the user, finds

their sum and average and prints out the 3 numbers, their sum and their

average with labels

Input: 3 integers in response to a prompt

Output: intro, prompt, echo of entered data, sum of entered data, average of entered

data

General Comments: program does not error check for correctness of entered data values

}

{ Pascal has 2 forms of comments - a single line comment delimited by (* and

*) and a multi-line comment delimited by curly braces

}

{ All Pascal programs begin with the reserved word program followed by an identifier

and an optional parameter list specifying input and output devices (if any) followed

by a semi-colon. This is called the header statement.

If there is to be input, then input should be a parameter in the header statement

If there is to be output, then output should be a parameter in the header statement

input and output refer to the default input and output devices: keyboard and screen

whether they appear as (input, output) or (output, input) doesn't matter

}

program homework4 (input, output);

{ All variables used in a Pascal program must be declared. The declarations are

preceded by the reserved word var. In this program there are four integer identifiers.

They are separated by commas and followed by a colon and then their type and then

a semi-colon. There is one real identifier. Note that the reserved word var is not

repeated

}

var number1,number2, number3, sum : integer;

average : real;

(* the statements of the program follow the reserved word begin *)

begin

{ the writeln statement prints the desired output to the screen. After printing

the values, it moves the cursor to the next line.

}

writeln (' this program will ask you to enter three integers and will find ');

writeln (' their sum and average and echo the integers, and print the sum ');

writeln (' and average with appropriate labels ');

{ the write statement leaves the cursor on the line (does not insert a CR/LF )

output literals are surrounded by single quotes

}

write (' please enter an integer and hit return : ');

{ the readln statement picks up a value entered by the user and then moves the

cursor to the start of the next line

}

readln (number1);

write (' please enter an integer and hit return : ');

readln (number2);

write (' please enter an integer and hit return : ');

readln (number3);

{ Note that in Pascal, strings and identifiers can be in the same writeln statement

(unlike in Java) and they are separated by commas

}

writeln (' the numbers you entered are ', number1, ', ', number2, ', and ', number3);

{ write, writeln, read and readln are calls to predefined procedures and have

variable length parameter lists. writeln ( ' something '); is equivalent to

writeln (output, ' something '); and readln (' something '); is equivalent to

readln (input, ' something ');

}

(* the assignment operator in Pascal is colon-equal := *)

sum := number1 + number2 + number3;

(* the slash (/) is the division operator that produces a real result *)

average := sum / 3.0;

{ the :5:3 after average in the ouput statement formats the output so that it does

not appear in the default, exponential format

}

writeln (' the sum is ' , sum , ' and the average is ' , average:5:3);

(* the main program in Pascal ends with an end. (end followed by a period) *)

end.