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SURVEY OF PRORAMMING LANGUAGES


Table of Contents

Unit 1:    Introduction

Unit 2: Program Structure, Comment, Variables and Datatype

Unit 3: Programs with Lab Examples


UNIT 1

INTRODUCTION

1.1    INTRODUCTION: 

The goal of this tutorial under Survey of programming languages is to teach you the practical general overview, and fundamental concept of programming languages and comparing syntactic (syntax) and semantic concepts underlying programming languages like: Pascal, Java and C++. We will be implementing programs using at least three different programming languages. their syntax: bindings and scope, data types and type checking, functional scheme, expression of assignments and statements, control structure (selection statement and loop statement) etc. This will harness and reinforce the knowledge of students on how to be familiar with the programming language differences.

There are two ways to write programs, console application (it focuses on texts only) and Graphical User Interface application (it focuses on using controls like label, textbox, button, separator, panel, frame etc.). However, this tutorial will focus on the use of console application.

1.2    Identifier, Binding and Scope

Identifier: Identifier is a name that allows programmer to refer to variables, constants, functions, types, operations etc. in a program.

Binding: Binding association of an identifier with an object (i.e. assigning datatype to an identifier). There is static and dynamic binding. Static binding uses Type (datatype) information for binding while Dynamic binding uses Objects to resolve binding. In addition, if linking between method call and method implementation is resolved at compile time then we call it static binding or If it is resolved at run time then it dynamic binding.

Scope: The lifetime of a binding of a name to an object. There is local and global variable. A local variable is declared inside a function and can only be accessed within the function in which it is declared while A global variable is declared outside of a function and can be accessed anywhere in the program.


1.3    Comparison

 




UNIT 2

PROGRAM STRUCTURE, COMMENT, VARIABLE AND DATATYPE

2.1    Program Structure

Program structure gives the overview of a program for a particular programming language, and also with emphasis on the individual components of the program and the interrelationships between these components.

Pascal

program filename;

var

//variable declaration

begin

//statements to be executed

end.

 

Java

public class filename {

    public static void main(String[] args) {

        //statements to be executed

    }

}

 

C++

#include <iostream>

using namespace std;

int main() {

  //statements to be executed

  return 0;

}

 

2.2    Comment

Comment is used to add additional information to a program. It helps to indicate what needs to be done either instantly or after. It helps to explain the function of a particular line or lines of code.

2.2.1    Single line commenting

Single line commenting

// Pascal program to display your name

//Java Program to display your name

// C++ Program to display your name

 

2.2.2    Multiple line commenting (it allows blocks of comment in multiline)

{

Author: Dmac Tutor

Written Date: Mar 30, 2023

Topic: Pascal program to display your name

}

/*

Author: Dmac Tutor

Written Date: Mar 30, 2023

Topic: Java program to display your name

*/

Author: Dmac Tutor

Written Date: Mar 30, 2023

Topic: C++ program to display your name

*/

 

2.3    Variable

Variable is used to store values in a program. When you create variable, it resides in the memory of the computer. Variable is a value that can change.

2.3.1    Rules for naming identifier

-         Give meaning names (your identifier must tally with what your program is all about)

-         Start with letter (a-z, or A-Z), number (0-9) or underscore

-         Identifier cannot start with a number (0-9)

-         Keywords or reserved words cannot be used to create identifier

 

2.4    Datatype

A data type specifies which type of value a variable has, what type of value can be stored in it considering the type of mathematical, relational or logical operations that can be applied to the variable without causing an error. Two categories of datatypes are primitive and non-primitive. We will focus on primitive.

Pascal

string – stores combination of letters, numbers and special character

char – stores single character like letter, number and special character

integer, longint – stores whole number

real – stores decimal numbers

boolean – stores true or false value

 

Java

String – stores combination of letters, numbers and special character (TIP: Java String starts with capital ‘S’)

char – stores single character like letter, number and special character

int, long – stores whole number

float, double – stores decimal numbers

boolean – stores true or false value

 

C++

string – stores combination of letters, numbers and special character

char – stores single character like letter, number and special character

int – stores whole number

float, double – stores decimal numbers

bool – stores true or false value

 

2.5    Variable declaration

Variable declaration is a statement used to specify the variable name and its data type.

Pascal

Syntax

variableName : datatype;

//single variable

firstname : string;

age : integer

//multiple variables

firstname, surname, address : string;

age, level : integer

 

Java

Syntax

datatype variableName;

//single variable

String firstname;

int age;

//multiple variables

String firstname, surname, address;

int age, level;

 

C++

Syntax

datatype variableName;

//single variable

string firstname;

int age;

//multiple variables

String firstname, surname, address;

int age, level;

 

2.6    Variable Initialization

Initializing a variable means to specify an initial value to assign to it. A variable that is not initialized is stored with a default value. int is stores 0, float stores 0.0, string stores null, char stores ‘\u0000’, boolean stores false. Two types of variable initialization are explicit and implicit. Explicit initialization is when you assign a value in a program in the source editor before compiling the program, while implicit initialization is when you supply value after the program compiles.

Pascal

Syntax

The assignment operator of Pascal is colon and equal to. It assigns value to the variable for storage.

variableName := value;    

//single variable

firstname := “dmactutor”;

age := 20;

 

Java

Syntax

The assignment operator of Java is equal to.

variableName = value;

firstname = “dmactutor”;

age = 20;

 

C++

Syntax

The assignment operator of C++ is equal to.

variableName = value;

firstname = “dmactutor”;

age = 20;

 

2.7    Variable Declaration and Initialization

If you don’t want to first declare a variable then initialize it, you can also make a 2-in-1 statement, by declaring and initializing a variable at the same time.

Pascal

Syntax

The colon will not be present, you use only equal to in Pascal to perform 2-in-1.

variableName : datatype = value;    

//single variable

firstname : string = “dmactutor”;

age : integer = 20;

TIP: Pascal allows multiple variables to be declared, but I have not gotten the way for multiple variables to be declared and initialized at the same time.

//multiple variables

firstname, surname : string;

 

Java

Syntax

datatype variableName = value;

String firstname = “dmactutor”;

int age = 20;

//multiple

int age = 20, level = 4;

 

C++

Syntax

datatype variableName = value;

String firstname = “dmactutor”;

int age = 20;

//multiple

int age = 20, level = 4;

 

2.8    Constant Variable Declaration and Initialization

If you don’t want a value to change, you can declare it as constant, or if you want to use a value repeatedly in program, for example pi = 3.14, the value is constant.

Pascal

Syntax

This works with or without using the var keyword. Use the const keyword.

const variableName  = value;    

const age = 20;

 

Java

Syntax

Use the const keyword.

const datatype variableName = value;

const int pi = 3.14;

 

C++

Syntax

Use the const keyword.

datatype variableName = value;

String firstname = “dmactutor”;

int age = 20;


 

UNIT 3

CODE IMPLEMENTATION USING PJC (Pascal, Java, C++)

3.1       PROGRAMS WITH LAB EXAMPLES

TIP: At some point, you might have issue running C++ program using internet enabled compiler, I will recommend you run your code on Dev C++, to be on a safer side and to avoid giving yourself headache to debug error.

3.1.1   Lab 1 – program to display name and age

Pascal

program lab1;

begin

  writeln('dmac tutor');

  writeln(18);

end.

TIP: In the program above, surround the characters with single quotes, if your display string. If you use double quotes, it will generate error. To display a number, you don’t need put it in quote.

Java

class lab1 {

    public static void main(String[] args) {

        System.out.println("dmactutor \n");

        System.out.println(18);

    }

}

TIP: In the program above, we use escape sequence \n so that 18 will appear on a new line.

C++

#include <iostream>

using namespace std;

int main()

{

    cout << "dmactutor \n";

    cout << 18;

    return 0;

}

 

3.1.2   Lab 2 – program to declare and initialize name and age

Pascal

program lab2;

var

//declare variables

    fullname : string;

    age : integer;

begin

//initialize variables

  fullname := 'dmactutor';

  age := 18;

 

//print content of variables

  writeln(fullname);

  writeln(age);

  //to make it more descriptive

  writeln('Your name is:: ', fullname);

end.

TIP: In the above program, don’t wrap variables in quote

Java

class lab2 {

    public static void main(String[] args) {

        String fullname;

        int age;

        fullname = "dmactutor";

        age = 18;

       

        System.out.println(fullname);

        System.out.println(age);

       

        //to make it more descriptive

        System.out.println("Your name is::"  + fullname);

    }

}

 

C++

#include <iostream>

using namespace std;

 

int main()

{

    string fullname;

    int age;

    fullname = "dmactutor";

    age = 18;

    cout << fullname <<endl;   //endl creates a new line like: cout << fullname <<"\n";

    cout << age <<endl;

   

    //to make it more descriptive

    cout << "Your name is:: " << fullname;

    return 0;

}

 

3.1.3   Lab 3 – program to declare and accept input for variables name and age

Pascal

program lab3;

var

//declare variables

    fullname : string;

    age : integer;

begin

//display action for the user and accept input

  writeln('Please enter your full name');

  readln(fullname);

 

  writeln('Please enter your age');

  readln(age);

 

//print content of variables

  writeln(fullname);

  writeln(age);

 

end.

 

Java

import java.util.*;

class lab3 {

    public static void main(String[] args) {

        //create scanner object sc (you can use any variable of your choice)

        Scanner sc = new Scanner(System. in);

 

        //display action for the user and accept input

        System. out. println("Please enter your full name:: ");

        String fullname = sc.nextLine();

       

        System. out. println("'Please enter your age:: ");

        int age = sc.nextInt();

       

        System.out.println(fullname);

        System.out.println(age);

       

    }

}

TIP: You have to import the libarary that contains Scanner, using java.util.*; helps you to access many libraries at the same time. Then we need to create a scanner object ‘sc’ which is associated with our variables: fullname and age, along with their scanner method. String uses nextLine(), int uses nextInt()

C++

#include <iostream>

using namespace std;

 

int main()

{

    string fullname;

    int age;

    cout<<"Please enter your full name:: ";

    cin >> fullname;

   

    cout<<"Please enter your age:: ";

    cin >> age;

   

    cout << fullname <<endl; 

    cout << age <<endl;

   

    return 0;

}

 

3.1.4   Lab 4 – program to add two numbers (arithmetic operation)

Pascal

program lab4;

var

//declare variables

    fnum, snum, result : integer;

begin

//display action for the user and accept input

  writeln('Enter first value');

  readln(fnum);

 

  writeln('Enter second value');

  readln(snum);

 

  //processing

  result := fnum + snum;

 

//print content of variables

  writeln('The answer is:: ', result);

 

end.

 

Java

import java.util.*;

public class lab4 {

    public static void main(String[] args) {

        //create scanner object sc (you can use any variable of your choice)

        Scanner sc = new Scanner(System. in);

       

        System. out. println("Enter first value:: ");

        int fnum = sc.nextInt();

       

        System. out. println("Enter second value:: ");

        int snum = sc.nextInt();

       

        int result = fnum + snum;

       

        System.out.println("The answer is:: " + result);

        

    }

}

 

C++

#include <iostream>

using namespace std;

 

int main()

{

    int fnum, snum, result;

   

    cout<<"Enter first value:: ";

    cin >> fnum;

   

    cout<<"Enter second value:: ";

    cin >> snum;

   

    result = fnum + snum;

   

    cout << "The answer is:: " <<result; 

       

    return 0;

}

TIP: If you encounter ths error: id returned 1 exit status. The possible causes of this error are: A syntax error in the C++ program, A mismatch between the compiler and the library, An incorrect link to a library, An incorrect or missing header file. Solution, open another file, type your codes then compile and run again.

3.1.5   Lab 5 – program to compute mathematical formulas getting decimals. Program for bmi (body max index).

The appropriate datatype for pascal: real, Java: double, C++: float) and formatting it to two decimal places. Test it with integer for pascal and int for Java and C++ to see what will happen.

Pascal

 

program lab5;

var

//declare variables

    weight, height, resultBmi : real;

begin

//display action for the user and accept input

  writeln('Enter weight value in KG:: ');

  readln(weight);

 

  writeln('Enter height value in meters from (0-2):: ');

  readln(height);

 

  //processing

  resultBmi := weight / (height * height);

 

//before formatting

  writeln('Your body mass index is:: ', resultBmi);

//after formatting

  writeln('Your body mass index is:: ', resultBmi:0:2);

 

end.

TIP: 0:2, the zero indicate the number of digit spaces to be reserved for the whole number part (replace the 0 with 1,2,3,4 etc to see the output), while two indicate that the number should be approximated to two decimal places. Pascal don’t allow ** or ^ as power operator.

Java

import java.util.*;

public class lab5 {

    public static void main(String[] args) {

        //create scanner object sc (you can use any variable of your choice)

        Scanner sc = new Scanner(System. in);

       

        System. out. println("Enter weight value in KG:: ");

        double weight = sc.nextDouble();

       

        System. out. println("Enter height value in meters from (0-2):: ");

        double height = sc.nextDouble();

       

        double resultBmi = weight / (height * height);

       

        //before formatting

        System.out.println("Your body mass index is::  " + resultBmi);

        //after formatting

        System.out.println("Your body mass index is:: " + String.format("%.2f", resultBmi));        

        

    }

}

TIP: To round up the number to two decimal places, we use format() method in java. Java allows ** as power operator.

C++

#include <iostream>

using namespace std;

 

int main()

{

    float weight, height, resultBmi;

   

    cout<<"Enter weight value:: ";

    cin >> weight;

   

    cout<<"Enter height value:: ";

    cin >> height;

   

    resultBmi = weight / (height * height);

   

    //before formatting   

    cout << "Your body mass index is:: " <<resultBmi <<endl; 

    //after formatting   

    cout << "Your body mass index is:: ";

            printf("%.2f", resultBmi);

       

    return 0;

}

 

3.1.6   Lab 6 – program to compute mathematical formulas using inbuilt function. Program for Pythagoras theorem to find the hypothenus.

We will use Sqrt() built-in function. The Sqrt() function returns the square root of its argument.

Pascal

program lab6;

var

//declare variables

    opp, adj, hyp : real;

begin

//display action for the user and accept input

  writeln('Enter opposite value');

  readln(opp);

 

  writeln('Enter adjacent value');

  readln(adj);

 

  //processing

  hyp := Sqrt((opp*opp) + (adj*adj));

 

  writeln('Hypothenuse result is:: ', hyp:5:2);

 

end.

TIP: your Sqrt() in pascal must start with capital “S”

Java

import java.util.*;

import java.lang.*;

public class lab6 {

    public static void main(String[] args) {

        //create scanner object sc (you can use any variable of your choice)

        Scanner sc = new Scanner(System. in);

       

        System. out. println("Enter opposite value:: ");

        double opp = sc.nextDouble();

       

        System. out. println("Enter adjacent value:: ");

        double adj = sc.nextDouble();

       

        double hyp = Math.sqrt((opp*opp) + (adj*adj));

         

        System.out.println("Hypothenuse result is:: " + String.format("%.2f", hyp));        

        

    }

}

TIP: To use the Math sqrt() function in Java, you must import java.lang.*; and you must associate your variables with Double. Any other datatype with the math inbuilt function will generate error.

C++

#include <iostream>

#include <cmath>

using namespace std;

 

int main()

{

    float opp, adj, hyp;

   

    cout<<"Enter opposite value:: ";

    cin >> opp;

   

    cout<<"Enter adjacent value:: ";

    cin >> adj;

   

    hyp = sqrt((opp*opp) + (adj*adj));   

      

    cout << "Hypothenuse result is:: ";

            printf("%.2f", hyp);

       

    return 0;

}

TIP: To use the sqrt() function in C++, you must call #include <cmath>

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