ADARSH VIDYA KENDRA NAGERCOIL COMPUTER SCIENCE. Grade: IX C++ PROGRAMMING. Department of Computer Science 1

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1 NAGERCOIL COMPUTER SCIENCE Grade: IX C++ PROGRAMMING 1

2 C++ 1. Object Oriented Programming OOP is Object Oriented Programming. It was developed to overcome the flaws of the procedural approach to programming. In OOP the problem is divided into a number of entities called objects. The data is passed directly to these objects. These objects can interact with each other. A Language is called as OOP Language if it supports all the Features of the OOP Language Objects: Essence of OOP OOP is a powerful way to create programs, and it makes the program you write more useful. Consider Word processing software. It could be divided into various objects: A document object, which is the area where you type in text. A spell checking object, which looks over the document to find spelling errors. A printer object, which handles printing of the document. A menu object, a mouse object and many other objects Benefits of OOP Object Oriented Programming is being used extensively for software development today. This technology makes programming easier and error - free. Software is easily managed, as it is divided in various objects, which can easily partition the whole project. The upgrading of software is also easy, as only some objects need to be replaced instead of the whole software. Also we can write programs from the standard working programs by extending their behaviour rather than starting from scratch. For these reasons, OOP is becoming a norm for software development Need to Write C++ Programs Before you can start to write C++ programs, you need to acquire some kind of programming software. Although several products are available for the development of C++ programs, the starting place is either Turbo C++ package or Microsoft Visual C++ package, which includes C++ programming environment and a C++ compiler. Every Programming language requires a compiler or interpreter. The Compiler takes a computer program and translates it into a binary form that the computer understands. ie. in 0 & 1 form. Several free C++ compilers are available on the internet. Some of which might be difficult to operate for amateurs. 2

3 Answer the following 1. Write short note on C Write the benefits of C Explain the various objects of OOPs? ************************* 2. Structure of a C++ Program Every C++ program contains a number of several building blocks as functions. Each function of it performs task independently. A function is subroutine that may consists of one or more statements. A C++ program comprises of the following sections. Include Header File Sections Global Declaration Section /* Comments */ main() /* comments */ Declaration Part Executable Part User defined functions 2.1. Include Header File Section C++ program depends upon some header files for function definition. Each header file by default is extended with.h. The file should be included using #include directive. Example: #include<iostream.h> #include<conio.h> 2.2. Global Declaration This section includes some variables that are used in more than one function. These variables must be declared outside of all the functions. 3

4 2.3. Function main() Every program written in c language must contain main( ) function. Empty parenthesis after main is necessary. The function main() is the starting point of every C++ program. The execution of the program always begins with the function main (). Except the main () function, other sections may not be necessary. The program execution starts with opening brace and ends with closing brace. Between this braces the programmer should declare the declaration and executable part Declaration part The declaration part declares the entire variables that are used in executable part. The initialization means providing initial value to the variable Execution part This part contains the statements following the declaration of the variables. This part contains a set of statements or a single statement. These statements are enclosed between the braces User defined functions The functions defined by the user are called user-defined functions. These functions are generally defined after main() function. This portion is not compulsory Writing C++ code The proper way of writing C++ code is called the Syntax. Syntax is a mixture of: C++ keywords like int, for and return. Constants and variables Operators like +(arithmetic addition ), (logical or ) and & (the address of operator) Answer the following 1. Write the structure of C++ program and explain? 2. What is the role of braces in C++ program? 3. What header file must you include with your source file to use cout and cin? 4. Why is function main() special? ********************** 4

5 3. Input and Output statements 3.1.Outputting Values: To output a value, we use cout. Here s an example: cout<< the value of x is \n <<x; All most all the text within the quote marks is printed out onto the screen except escape char. Instead of printing out the variable name, the numerical value of x is printed out. The \n is a special character- the new line character. In C++ we use cout statement to display the output and cin statement to take the input. Both of these tools are in a header file called iostream.h. So as the first line of our program we have to include the header file iostream.h. This can be done by using the statement #include. This statement is meant for the pre-processor and not the C++ Compiler. Every statements starting with the symbol # is meant for pre-processor. These are called as pre-processor directives. Whenever we need to display anything on the screen we can use the cout statement. cout is just like a projector. Anything send to the cout will be displayed on the screen of the computer. If we want to display a group of words as such on the screen we will have to enclose that in double quotations and send it to the cout. Eg: cout<< Hello this is displayed on the screen ; When this gets executed we will see the group of words on the screen. The symbol << is called insertion operator. If there is more than one group of words it should be inserted in to the cout using multiple insertion operators. Eg: cout<< One group << second group << third group ; This type of usage of multiple insertion operators is called cascading.if we want to show any matter stored in a memory position to the screen using cout we will have to type in the name of memory position without enclosing the name in double quotations Input cin is used in the same way to input some value from the keyboard. Ex: cin>>a; 5

6 The statement directly assigns the value entered by the keyboard to the variable a. Here is a sample program demonstrating the use of a variable: #include <iostream.h> int main() inta,b,c; /* Declare variables*/ cout<<"enter two integers separated by a space: "; cout<< and I will work out their sum!\n ; cin>> a>>b; c=a+b; cout<<a<< plus <<b<< is equal to <<c <<"\n"; return 0; 3.3. Commenting the code You can add comments to your code by enclosing your remarks within /* and */ or by placing a // before a line. However, nested comments ie. Placing a comment within comment within a comment is not allowed 3.4. Advantages of commenting They can be used to tell the person viewing the code which part of the code does what. This is helpful when you revisit the code at a later date. The compiler ignores all the comments. This means that comments do not affect the efficiency of the program. You can use /* and */ to comment out sections of the code when it comes to finding the errors, instead of deletion. Answer the following 1. What are input and output statements? 2. What is the input operator >> and output operator << called? 3. Write the advantages of comments? 6

7 Try in your lab 1. Write a C++ program to print welcome to C++ program. 2. Write a C++ program to find the sum of two numbers. 3. Write a C++ program to find the sum and average of two numbers. **************************** 4. Constants and Variables 4.1. Constants Constants are data items whose values cannot be changed. A constant is of numeric or nonnumeric type. Numeric constants consist of only numbers, either whole numbers or decimal numbers. Integer, floating-point are numeric constants Integer Constant Integer Constant must have at least one digit and must not contain any fractional part. May be prefixed with a + or sign A sequence of digits starting with 0 (zero) is treated as Octal constant Ex. 010 = 8 ( [8] 10 = [10] 8 ) A sequence of digits starting with 0xis treated as hexadecimal integer. Ex. 0xF = 15 ( [15] 10 = [F] 16 ) Floating Point Constant Floating Point Constant is a signed real number. It includes an integer portion, a decimal point, a fractional portion and an exponent. While representing a floating point constant the integer portion or the decimal portion can be omitted but never both. For example is a valid floating point (Real) constant. It can be represented in exponent form as follows: 5.864E1 => x 101 => E-2 => 5864 x 10 2 => E2 => x102 => The letter E or e is used to represent the floating-point constant exponent form Character Constant Character constant is a constant that contains a single character enclosed within single quotes. It can be any character as defined in the character set of C++ language (alphabet, numeral, mathematical, relational or any other special character as part of the ASCII set). Certain special 7

8 characters like tab, backspace, line feed, null, backslash are called as non-graphic character constants. These characters are represented using escape sequences. Escape sequences are represented using characters prefixed with a backslash Escape Sequence Nongraphic Character \a - Bell \b - Back space \n - New line/ line feed \t - Horizontal tab \v - Vertical tab \\ - Back slash \ or \ - Single / double quotes \o - Octal number \x - Hexadecimal number \0 - Null 4.3. Variables There are several rules that you must follow when naming variables: Variables name rules Example Cannot start with a number 2times Can contain a number elsewhere Times2 Cannot contain any arithmetic operators A *b+c or any special punctuation marks! Result 99 Cannot be a C++ keyword while Cannot contain a space Hello world Can start with or contain an underscore Who_is_that Can be of mixed cases AvkCbse 4.4. Expressions and Statements A statement is a building block of a program. For example the assignment statement int a=10; 8

9 This is also an expression and has the value 10. If we write this code int b= (a=10) ; Both a and b will be set to the value Conditional Expression A conditional expression is one which evaluates as true (a non zero value) or false (0). True is almost always 1 but any non zero value is also true! A zero value is false, anything else is true. Ex: #include <iostream.h> int main() int a=10; int b=( a = 10) ; int c=( a==10) ; cout<< "Value of b is " << b <<endl ; cout<< "Value of c is " << c <<endl ; return0; Compile and run the example above. It should print out the following. Value of b is 10 Value of c is The const Keyword The const keyword is used to create a read only variable. Once initialized, the value of the variable cannot be changed but can be used just like any other variable. const syntax : main() const float pi = 3.14; The const keyword is used as a qualifier to the following data types 9

10 int float char double constint degrees = 360; const float pi = 3.14; const char quit Answer the questions: = 'q'; 1. How are integer constants represented in C++? Explain with examples. 2. What are character constants in C++? How are these implemented? 3. What is escape sequence? Give example. 4. What are the rules for naming a variable? 5.1. C++ character set ****************************** 5. Data Types Like the C language, C++ also comprises a character set from which the tokens (basic types of elements essential for programming coding ) are constructed. The character set comprises of A.. Z, a.. z, 0.. 9, +, -, /, *,\, (, ), [, ],,, =,!=, <, >,., ; : %,!, &,?, _, #, <=, white space, horizontal tab, carriage return and other characters. Let us write a program to print Hello using chars #include<iostream.h> int main() char a,b,c,d,e; a= H ; /* correct way*/ /* a = H is wrong */ b= e ; c= l ; d= I ; e= o ; cout<<a<<b<<c<<d<<e<< \n ; return 0; This program just prints Hello as its output. 10

11 5.2. Integers Whole numbers are integers(called int). The int variable type can store values from to in C++. Valid integer assignment instructions is int a= 8 is invalid. They occupy 2 bytes in the computer memory Floating Point numbers: Integers are great for counting whole numbers, but sometimes we need to store very large numbers, or numbers with a fractional component. A floating point type variable is a variable that can hold a real number, such as 4.0, 2.5, 3.33, or There are three different floating point data types: float, double, and long double. A float is usually 4 bytes and a double 8 bytes, but these are not strict requirements, so sizes may vary. Long doubles were added to the language after it s release for architectures that support even larger floating point numbers. But typically, they are also 8 bytes, equivalent to a double. Floating point data types are always signed (can hold positive and negative values). Here are some declarations of floating point numbers: 1 float fvalue; 2 double dvalue; 3 long double dvalue2; The floating part of the name floating point refers to the fact that a floating point number can have a variable number of decimal places. For example, 2.5 have 1 decimal place, whereas has 4 decimal places. When we assign numbers to floating point numbers, it is convention to use at least one decimal place. This helps distinguish floating point values from integer values. 1 2 int nvalue = 5; // 5 means integer float fvalue = 5.0; // 5.0 means floating point 5.4. Declaring Variables in C++ To declare a variable you use the syntax "type <name>;". Here are some variable declaration examples: Int x; char letter; float the_float; 11

12 It is permissible to declare multiple variables of the same type on the same line; each one should be separated by a comma. int a, b, c, d; The declaration of a variable is always followed by a semicolon Common Errors when Declaring Variables in C++ If you attempt to use a variable that you have not declared, your program will not be compiled or run, and you will receive an error message informing you that you have made a mistake. Usually, this is called an undeclared variable Case Sensitivity Now is a good time to talk about an important concept that can easily throw you off: case sensitivity. Basically, in C++, whether you use uppercase or lowercase letters matters. The words Cat and cat mean different things to the compiler. In C++, all language keywords, all functions and all variables are case sensitive. A difference in case between your variable declaration and the use of the variable is one reason you might get an undeclared variable error. Answer the questions: 1. Explain integer data types 2. Explain floating point numbers 3. How will you declare a variable? *************************** 6. Operators 6.1. Arithmetic Operators Arithmetic Operators are used to perform mathematical operations. The list of arithmetic operators are :+, -, * multiplication operator, / division operator, % modulus operator - gives the remainder of an integer division, +=, -=, *=, /=, %=. Arithmetic expressions are formed using arithmetic operators, numerical constants/variables, function call connected by arithmetic operators Assignment operator a = 5; takes the slot reserved for a and puts the value 1 into it. 12

13 6.3. Arithmetic Assignment Operators Examples: a =+b; is the same as x=x+y; a /= 5; (a = a/5) a *= 2 ( a = a * 2) a %= 5 ( a = a/5) a = b + pow(x,y) ( a = b + x y ) 6.4. Increment and Decrement operators a++; - (Post increment operator. Equivalent to a = a+1) a- - ; - (Post decrement operator. Equivalent to a = a-1) ++a; - (Pre increment operator. Equivalent to a = a+1) - - a ; - (Pre decrement operator. Equivalent to a = a 1) Operators are executed in the order of precedence. The operands and the operators are grouped in a specific logical way for evaluation. This logical grouping is called as association. Answer the questions: 1. Write a program to find the area and circumference of circle 2. Write a program to find the area of square 3. Write a program to find the area of rectangle 4. Write a program to find the area of triangle 5. Write a program to calculate simple interest 6.5.Relational Operators Relational Operators are used to compare values. The lists of relational operators are = = equal to > greater than < lesser than >= greater than or equal to <= lesser than or equal to!= not equal to Relational operators are used to compare numeric values. A relational expression is constructed using any two operands connected by a relational operator. For example the relational operators are used to construct conditions such as 13

14 10 > <= != = = 9 The result of a relational operation is returned as true or false.the numeric constant zero (0) represents False value, and any nonzero constant represents true value. The above expressions output will be 0 (10 > 20 is false ) ; 1 ( < 1005 is evaluated to True hence any non zero constant) ; 1 (99!= 99.5 will be evaluated to True hence non zero constant) 1 ( 9 = = 9 will be evaluated to true, hence the output will be non zero constant) 6.6. Logical Operators (Boolean Operators) Logical operators combine the results of one or more operators combines the results of one or more conditions. The various logical operators are &&(AND) (OR)! (NOT) AND operator The logical AND operator (&&) returns the boolean value true if both operands are true and returns false otherwise. The operands are implicitly converted to type bool prior to evaluation, and the result is of type bool. Logical AND has left-to-right associatively. The operands to the logical AND operator need not be of the same type, but they must be of integral or pointer type. The operands are commonly relational or equality expressions. The first operand is completely evaluated and all side effects are completed before continuing evaluation of the logical AND expression OR operator The second operand is evaluated only if the first operand evaluates to true (nonzero). This evaluation eliminates needless evaluation of the second operand when the logical AND expression is false. 14

15 The logical OR operator () returns the boolean value true if either or both operands is true and returns false otherwise. The operands are implicitly converted to type bool prior to evaluation, and the result is of type bool. Logical OR has left-to-right associatively. The operands to the logical OR operator need not be of the same type, but they must be of integral or pointer type. The operands are commonly relational or equality expressions. The first operand is completely evaluated and all side effects are completed before continuing evaluation of the logical OR expression. The second operand is evaluated only if the first operand evaluates to false (0). This eliminates needless evaluation of the second operand when the logical OR expression is true. Ex: cout (x == w x == y x == z)); In the above example, if x is equal to either w, y, or z, the second argument to the printf function evaluates to true and the value 1 is printed. Otherwise, it evaluates to false and the value 0 is printed. As soon as one of the conditions evaluates to true, evaluation ceases NOT operator This operator negates the expression. If the expression returns true this operator changes it to false and if the expression returns false, it changes it to true. Answer the questions: 1. Explain relational operator. 2. Explain logical operator. Write a program to find the maximum among two integers. Max = ((a+b) + abs(a-b))/2 ************************* 7.1.IF statement 7. Control Structure The if statement allows you to control if a program enters a section of code or not based on whether a given condition is true or false. One of the important functions of the if statement is that it allows the program to select an action based upon the user's input. For example, by using an if statement to check a user entered password, your program can decide whether a user is allowed access to the program. 15

16 The structure of an if statement is as follows: if (condition/expression) Action block1; Example: If (5<10) cout<< Five is now less than ten ; Simple if statement program # include <iostream.h> # include <conio.h> void main() int a; clrscr(); cout<< \nenter a number ; cin>> a; if ( a%2 == 0) cout<< \nthe given number << a << is even ; getch(); 7.2. The Else statement: If the condition is not true, sometimes you want the program do something as a last resort. So, after if statement, you can use as else statement. Ex. /* to find the input number is even or odd */ # include <iostream.h> # include <conio.h> void main() 16

17 int a; clrscr(); cout<< \nenter a number ; cin>> a; if ( a%2 == 0) cout<< \nthe given number << a << is even ; else cout<< \nthe given number << a << is odd ; getch(); In the above program The given number 10 is even is printed if the expression is evaluated to true, otherwise statement following else option will be executed. Answer the questions: 1. Write a program to find the biggest among two given number 2. Write a program to find the smallest among two given number 3. Write a program to find the smallest among three given number **************************** 8. Nested if Another use of else is when there are multiple conditional statements that may all evaluate to true, yet you want only one if statement's body to execute. You can use an "else if" statement following an if statement and its body; that way, if the first statement is true, the "else if" will be ignored, but if the if statement is false, it will then check the condition for the else if statement. If the if statement was true the else statement will not be checked. It is possible to use numerous else if statements to ensure that only one block of code is executed. Syntax : if ( condition / expression ) // Execute these statements if <condition> is TRUE else if ( another condition/expression ) 17

18 // Execute these statements if <another condition> is TRUE and <condition> is FALSE Ex: #include <iostream.h> int main() int a,b; cout<< Input two integers separated with a space :\n ; cin>>a>>b; if (a==b) cout<<a<< is equal to <<b<< \n ; elseif (a<b) cout<<a<< is less than <<b<< \n ; else cout<<a<< is greater than <<b<< \n ; return 0; 9. The Conditional Operator 9.1 Conditional Operator (?:) (num1 > num2)? true : else -?: Is a ternary operator (num1>num2, true, false are the operands. A ternary operator (?:) is also called as conditional operator. The general syntax is E1?E2 : E3 where E1,E2,E3 are operands. E1 should essentially be of scalar type, E2 and E3 are values or statements. For example to assign the maximum value of the two values one can express it as :max = (num1 > num2)? num1 : num2; The variable max will take the value of num1 if num1 is greater than num2, otherwise max will be assigned with the value of num2. a?b:c Where a is a condition, b is an expression that is performed when the condition is true otherwise the expression in c is performed. Ex: x==10? cout<< x is equal to 10\n : cout<< x is not equal to 10\n ; 1. Write a program to find the biggest among 2 given number 18

19 10. Loop Types There may be a situation, when you need to execute a block of code several number of times. In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on. Programming languages provide various control structures that allow for more complicated execution paths. A loop statement allows us to execute a statement or group of statements multiple times and following is the general from of a loop statement in most of the programming languages: C++ programming language provides the following type of loops to handle looping requirements. 10. Loop Type Description while loop While loop repeats a statement or group of statements while a given condition is true. It tests the condition before executing the loop body for loop for loop execute a sequence of statements multiple times and abbreviates the code that manages the loop variable. 19

20 10.3.do...while do...while loop Like a while statement, except that it tests the condition at the end of the loop body nested loops Nested loop you can use one or more loop inside any another while, for or do..while loop While Loop A while loop statement repeatedly executes a target statement as long as a given condition is true. Syntax The syntax of a while loop in C++ is: while(condition) statement(s); Here, statement(s) may be a single statement or a block of statements.the condition may be any expression, and true is any non-zero value. The loop iterates while the condition is true.when the condition becomes false, program control passes to the line immediately following the loop. Flow Diagram Here, key point of the while loop is that the loop might not ever run. When the condition is tested and the result is false, the loop body will be skipped and the first statement after the while loop will be executed. 20

21 Example #include <iostream> using namespace std; int main () // Local variable declaration: int a = 10; // while loop execution while( a < 20 ) cout<< "value of a: " << a <<endl; a++; return 0; When the above code is compiled and executed, it produces the following result: value of a: 10 value of a: 15 value of a: 11 value of a: 16 value of a: 12 value of a: 17 value of a: 13 value of a: 18 value of a: 14 value of a: for Loop A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times. 21

22 Syntax The syntax of a for loop in C++ is: for ( initialization; condition; increment ) statement(s); Here is the flow of control in a for loop: a. The initialization step is executed first, and only once. This step allows you to declare and initialize any loop control variables. You are not required to put a statement here, as long as a semicolon appears. 22

23 b. Next, the condition is evaluated. If it is true, the body of the loop is executed. If it is false, the body of the loop does not execute and flow of control jumps to the next statement just after the for loop. c. After the body of the for loop executes, the flow of control jumps back upto the increment statement. This statement allows you to update any loop control variables. This statement can be left blank, as long as a semicolon appears after the condition. d. The condition is now evaluated again. If it is true, the loop executes and the process repeats itself (body of loop, then increment step, and then again condition). After the condition becomes false, the for loop terminates. Example: #include <iostream> int main () // for loop execution for(int a = 10; a < 20; a = a + 1 ) cout<< "value of a: " << a <<endl; return 0; When the above code is compiled and executed, it produces the following result: value of a: 10 value of a: 15 value of a: 11 value of a: 16 value of a: 12 value of a: 17 value of a: 13 value of a: 18 value of a: 14 value of a: 19 Unlike for and while loops, which test the loop condition at the top of the loop,the do...while loop checks its condition at the bottom of the loop do..while loop A do...while loop is similar to a while loop, except that a do...while loop is guaranteed to execute at least one time. 23

24 Syntax The syntax of a do...while loop in C++ is: do statement(s); while( condition ); Notice that the conditional expression appears at the end of the loop, so the statement(s) in the loop execute once before the condition is tested. If the condition is true, the flow of control jumps back up to do, and the statement(s) in the loop execute again. This process repeats until the given condition becomes false. Flow Diagram 24

25 Example #include <iostream.h> int main () // Local variable declaration: int a = 10; // do loop execution do cout<< "value of a: " << a <<endl; a = a + 1; while( a < 20 ); return 0; When the above code is compiled and executed, it produces the following result: value of a: 10 value of a: 15 value of a: 11 value of a: 16 value of a: 12 value of a: 17 value of a: 13 value of a: 18 value of a: 14 value of a: 19 Answer the questions: 1. Write a program to print 1 to Write a program to print all even numbers from 1 to Write a program to print all odd numbers from 20 to

26 Nested Loop A loop can be nested inside of another loop. C++ allows at least 256 levels of nesting. Syntax The syntax for a nested for loop statement in C++ is as follows: for (initialization; condition; increment ) for (initialization; condition; increment ) statement(s); statement(s); // you can put more statements. The syntax for a nested while loop statement in C++ is as follows: while(condition) while(condition) statement(s); statement(s); // you can put more statements. The syntax for a nested do...while loop statement in C++ is as follows: do statement(s); // you can put more statements. Do statement(s); while( condition ); 26

27 while( condition ); Example The following program uses a nested for loop to find the prime numbers from 2 to 100: #include <iostream.h> using namespace std; int main () int i, j; for(i = 2; i<100; i++) for(j = 2; j <= (i/j); j++) if(!(i%j)) break; // if factor found, not prime if(j > (i/j)) cout<< i << " is prime\n"; return 0; This would produce the following result: 2 is prime 3 is prime 5 is prime 7 is prime 11 is prime 13 is prime 17 is prime 19 is prime 23 is prime 29 is prime 31 is prime 37 is prime 41 is prime 43 is prime 47 is prime 53 is prime 59 is prime 61 is prime 67 is prime 71 is prime 73 is prime 79 is prime 83 is prime 89 is prime 97 is prime 27

28 Write a C++ program to print the following output ***************************** 28