GETTING STARTED WITH C++ C++ BASICS - 1 -

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1 - 1 - GETTING STARTED WITH C++ Programming is a core activity in the process of performing tasks or solving problems with the aid of a computer. An idealised picture is: PROBLEM COMPUTER SOLUTION Unfortunately things are not that simple. In particular, the PROBLEM" cannot be given to the computer using natural language. A computer cannot understand our language thatt we use in our day to day conversations, and likewise, we cannot understand the binary language that the computer uses to do its tasks Moreover, it has to contain information about how the problem is to be solved or the task is to be executed. Hence we need programming languages. C++ is a programming language which includes facilities for object-oriented programming, as well as for more conventional procedural programming. C++ was developed by Bjarne Stroustrup of AT&T Bell Laboratories in the early 1980's, and is based on the C language. COMPILATION AND LINKING OF C++ PROGRAM C++ BASICS C++ CHARACTER SET Character set is a set of valid language can recognize. Letters Digits Spac Special Characters { = %! Formatting characters TOKENS A token is the smallest element of a C++ program that is meaningful to the compiler. As in the English language, in a paragraph all the words, punctuation mark and the blank spaces are called Tokens. Similarly in a C++ program all the C++ statements having Keywords, Identifiers, Constants, Strings, Operators and the Special Symbols are called C++ Tokens. The programmer can write a program by using tokens. C++ uses the following types of tokens: Keywords, Identifiers, Literals, Punctuators, Operators 1. Keywords Keywords are reserved words. They have some specific meaning and are used for some specific task. The interpreter uses keywords to recognize the structure of the program, and they cannot be used as variable names. Some commonly used Keywords are given below: asm auto break case characters that a A-Z, a-z 0-9 ce + - * / ^ \ () [] =!= <> $, ; :! &?_ # <= backspace, horizontal tab, vertical tab, form feed, and carriage return catch char class const continue delete do double else extern inline int float friend goto if long operator private protected public return short signed sizeof struct switch template this typedef union unsigned virtual default enum for new register static Try void volatile while 2. Identifiers Symbolic names can be used in C++ for various data items used by a programmer in his program. A symbolic name is generally known as an

2 - 2 - something. The identifier is a sequence of characters taken from C++ character set. The rules for the formation of an identifier are: An identifier can consist of alphabets, digits and/or underscores. It must not start with a digit C++ is case sensitive that is upper case and lower case letters are considered different from each other. It should not be a reserved word. Examples of valid identifier names are i, my_name, name_23. Examples of invalid identifier names are 2things, S I, my-name, S.I., switch, sum. Programmer can choose the name of identifier whatever they want. However, if the programmer choose meaningful name for an identifier, it will be easy to understand and work on, particularly in case of large program. 3. Literals Literals (often referred to as constants) are data items that never change their value during the execution of the program. The following types of literals are available in C++. Integer-Constants Character-constants Floating-constants Strings-constants Integer Constants Integer constants are whole number without any fractional part. C++ allows three types of integer constants. Decimal integer constants : It consists of sequence of digits and should not begin with 0 (zero). For example 124, - 179, Octal integer constants: It consists of sequence of digits starting with 0 (zero). E.g. 014, 012. Hexadecimal integer constant: It consists of sequence of digits preceded by ox or OX. Character constants: A character constant in C++ must contain one or more characters and must be enclosed in single quotation marks. For example 'A', '9', etc. C++ allows non graphic characters which cannot be typed directly from keyboard, e.g., backspace, tab, carriage return etc. These characters can be represented by using an escape sequence. An escape sequence represents a single character. The following table gives a listing of common escape sequences. Escape Sequence Non-graphic Character \a Bell (beep) \n Newline \r Carriage Return \t Horizontal tab \0 Null Character Floating constants They are also called real constants. They are numbers having fractional parts. They may be written in fractional form or exponent form. A real constant in fractional form consists of signed or unsigned digits including a decimal point between digits. For example 3.0, -17.0, etc. String Literals A sequence of character enclosed within double quotes is called a string literal. String literal is by default (automatically) added with a special character \0' which denotes the end of the string. Therefore the size of the string is increased by one character. For example "COMPUTER" will re represented as "COMPUTER\0" in the memory and its size is 9 characters. 4. Punctuators The following characters are used as punctuators in C++: Brackets [ ] Opening and closing brackets indicate single and multidimensional array subscript. Parentheses ( ) Braces { Comma, Semicolon ; Colon : Asterisk * Equal sign = Opening and closing brackets indicate functions calls,; function parameters for grouping expressions etc. Opening and closing braces indicate the start and end of a compound statement. It is used as a separator in a function argument list. It is used as a statement terminator. It indicates a labeled statement or conditional operator symbol. It is used in pointer declaration or as multiplication operator. It is used as an assignment operator. Pound sign # It is used as pre-processor directive. 5. Operators Operators are special symbols used for specific purposes. Some important types of operators are: Arithmetical operators, Relational operators, Logical operators, Unary operators, Assignment operators, Conditional operators, Comma operator.

3 - 3 - DATA HANDLING BASIC DATA TYPES C++ supports a large number of data types. The built in or basic data types supported by C++ are integer, floating point and character. These are summarized in table along with description and memory requirement Type Byte Range Description int to Small whole number long int to Large whole number float 4 3.4x10-38 to 3.4x10+38 Small real number double 8 1.7x to 1.7x Large real number long double x to 3.4x Very Large real number char 1 0 to 255 A Single Character VARIABLES Variables are memory location in computer's memory to store data. To indicate the memory location, each variable should be given a unique name called identifier. Variable names are just the symbolic representation of a memory location. Examples of variable name: sum, car_no, count etc. To understand more clearly we should study the following statements: Total = 20.00; In statement a value has been stored in a memory location Total. Before a variable is used in a program, it has to be defined. This activity enables the compiler to make available the appropriate type of location in the memory. The definition of a variable consists of the type name followed by the name of the variable. For example, a variable Total of type float can be declared as shown below: float Total; INPUT/OUTPUT (I/O) C++ supports input/output statements which can be used to feed new data into the computer or obtain output on an output device such as: VDU, printer etc. It provides both formatted and unformatted stream I/O statements. The following C + + streams can be used for the input/output purpose. Stream Description cin console input cout console output In addition to the above I/O streams, two operators <<and >>are also used. The operator << is known as put to or bit wise shift operator. The operator>> is known as extraction or get from operator. cout << My first computer"; Once the above statement is carried out by the computer, the message "My first computer" will appear on the screen. cin is the standard input stream (keyboard) and it can be used to input a value entered by the user from the keyboard. However, the get from operator>> is also required to get the typed value from cin and store it in the memory location. Let us consider the following program segment: int marks; cin >> marks; In the above segment, the user has defined variable marks of integer type in the first statement and in the second statement he is trying to read a value from the keyboard. TYPE CONVERSION Converting an expression from one data type to another is known as type-conversion. There are two types of conversion in C Implicit conversion (Type Promotion) 2. Explicit conversion (Type Casting) Implicit conversion Data type can be mixed in the expression. For example double a; int b = 5; float c = 8.5; a = b * c; When two operands of different type are encountered in the same expression, the lower type variable is converted to the higher type variable. An implicit conversion is performed automatically by the compile when an expression needs to be converted into one of its compatible types. The following table shows the order of data types. DATA TYPE long double double float long int char Order of data types ORDER (highest) To (lowest) The int value of b is converted to type float and stored in a temporary variable before being multiplied by the float variable c. The result is then converted to double so that it can be assigned to the double variable a.

4 - 4 - Explicit conversion It is also called type casting. It temporarily changes a variable data type from its declared data type to a new one. It may be noted here that type casting can only be done on the right hand side of the assignment statement. T_Pay = double (salary) + bonus; Initially variable salary is defined as float but for the above calculation it is first converted to double data type and then added to the variable bonus. Explicit type conversion is a type conversion which is explicitly defined within a program (instead of being done by a compiler for implicit type conversion). CONSTANTS A number which does not change its value during execution of a program is known as a constant. Any attempt to change the value of a constant will result in an error message. A constant in C++ can be of any of the basic data types, const qualifier can be used to declare constant as shown below: const float pi = ; The above declaration means that Pi is a constant of float types having a value Examples of valid constant declarations are: const int rate = 50; const char ch = 'A'; STRUCTURE OF C++ PROGRAM The structure of a C++ program is given below: #include<header file> void main () { A C++ program starts with function called main ( ). The body of the function is enclosed between curly braces. The program statements are written within the braces. Each statement must end by a semicolon; (statement terminator). A C++ program may contain as many functions as required. However, when the program is loaded in the memory, the control is handed over to function main ( ) and it is the first function to be executed. // This is my first program is C++ /* this program will illustrate different components of a simple program in C++ */ # include <iostream.h> void main ( ) {cout <<"This is my first program in C++"; cout << "\n"; When this program is compiled, linked and executed, the following output is displayed on the VDU screen. This is my first program in C++ Various components of this program are discussed below: COMMENTS Comments are lines of code which are ignored by the compiler. Comments are included in a program to make it more readable. If a comment is short and can be accommodated in a single line, then it is started with double slash sequence in the first line of the program. For example: //Program to find Simple Interest However, if there are multiple lines in a comment, it is enclosed between the two symbols /* and */ For example: /* this program will illustrate different components of a simple program in C++ */ Use as many useful comments as you can in your program to: explain assumptions explain important decisions explain important details explain problems you re trying to solve explain problems you re trying to overcome in your program, etc. Code tells you how, comments should tell you why This is useful for readers of your program so that they can easily understand what the program is doing. Remember, that person can be you after six months! include <iostream.h> The lines in the above program that start with symbol # are called directives and are instructions to the compiler. The word include with '#' tells the compiler to include the file iostream.h into the file of the above program. File iostream.h is a header file needed for input/ output requirements of the program. Therefore, this file has been included at the top of the program. void main ( ) The word main is a function name. The brackets ( ) with main tells that main ( ) is a function. The word void before main ( ) indicates that no value is being returned by the function main (). When program is loaded in the memory, the control is handed over to function main ( ) and it is the first function to be executed.

5 - 5 - The curly brackets and body of the function main ( ) A C++ program starts with function called main(). The body of the function is enclosed between curly braces. The program statements are written within the brackets. Each statement must end by a semicolon, without which an error message in generated. SOME IMPORTANT TERMS Syntax error - The errors which are traced by the compiler during compilation, due to wrong grammar for the language used in the program, are called syntax errors. For example, cin<<a; // instead of extraction operator insertion operator is used. Run time Error - The errors encountered during execution of the program, due to unexpected input or output are called run-time error. For example - a=n/0; // division by zero Logical Error - These errors are encountered when the program does not give the desired output, due to wrong logic of the program. For example : remainder = a+b // instead of using % operator + operator is used. The preprocessor directive #include tells the complier to insert another file into your source file. In effect, #include directive is replaced by the contents of the file indicated. Compiler - It is a program which converts the program written in a programming language to a program in machine language. Linker - It is a program which links a complied program to the necessary library routines, to make it an executable program. Why char is considered as numeric data type? The memory implementation of char data type is in terms of the number code. Therefore, it is said to be another integer data type. Type Promotion: When two operands of different data types are encountered in the same expression, the variable of lower data type is automatically converted to the data types of variable with higher data type, and then the expression is calculated. For example: int a=98; float b=5; cout<<a/3.0; //converts to float type, since 3.0 is of float type. cout<<a/b; // converts a temporarily to float type, since b is of float type, and gives the result automatic type conversions. This can be done when the compiler does not do the conversions automatically. Type casting can be done to higher or lower data type. For example : cout<<(float)12/5; //displays 2.4, since 12 is converted to float type. Remember the type Promotion is performed by the compiler but a casting is done by the user Importance of main(): Whenever a C++ program is executed, execution of the program starts and ends at main(). The main is the driver function of the program. If it is not present in a program, no execution can take place. LAB EXERCISES - 1 LE 1.1 Write a program to find area and perimeter of a rectangle taking length as 10 and breadth as 20. LE 1.2 Write a program to find area and perimeter of a rectangle taking length and breadth from the user using input () function. LE 1.3 Write a program to convert Centigrade into Fahrenheit and vice versa. LE 1.4 Write a program to find lateral surface area, total surface area and volume of a cuboid. Take Length, Breadth and Height from the user using input () function. LE 1.5 Write a program to find lateral surface area, total surface area and volume of a Cone. Take Radius and Height from the user using input () function. LE 1.6 Write a program to find simple interest and compound interest. Take principal, rate and time from the user using input () function. LE 1.7 Write a program to swap two variables using a third variable. LE 1.8 Write a program to swap two variables without using a third variable. Type casting refers to the data type conversions specified by the programmer, as opposed to the

6 - 6 - OPERATORS Operators are special symbols used for specific purposes. C++ provides six types of operators. Arithmetical operators, Relational operators, Logical operators, Unary operators, Assignment operators, Conditional operators, Comma operator Arithmetical operators An operator that performs an arithmetic (numeric) operation: +, -,*,/, or %. For theseoperations always two or more than two operands are required. Therefore these operators are called binary operator. Relational operators The relational operators are used to test the relation between two values. All relational operators are binary operators and therefore require two operands. A relational expression returns zero when the relation is false and a nonzero when it is true. The following table shows the relational operators: Relational Meaning Operators < Less than <= Less than or equal to == Equal to > Greater than >= Greater than or equal to! = Not equal Logical operators The logical operators are used to combine one or more relational expression. The logical operators are Operators Meaning OR && AND! NOT Unary operators C++ provides two unary operators for which only one variable is required. For Example a = - 50; a = + 50; Here plus sign (+) and minus sign (-) are unary because they are not used between two variables. Assignment operator The assignment operator '=' stores the value of the expression on the right hand side of the equal sign to the operand on the left hand side. Example int m = 5, n = 7; int x, y, z; x = y = z = 0; in addition to standard assignment operator shown above, C++ also support compound assignment operators. Compound Assignment Operators C++ provides two special operators viz '++' and '--' for incrementing and decrementing the value of a variable by 1. The increment/decrement operator can be used with any type of variable but it cannot be used with any constant. With the prefix version of these operators, C++ performs the increment or decrement operation before using the value of the operand For instance the following code: int sum, ctr; sum = 12; ctr = 4; sum= sum + ++ctr; will produce the value of sum as 15 because ctr will be first incremented and then added to sum producing value 15. Similarly; the following code sum = 12; ctr = 4; sum = sum ctr will produce the value of sum as 15 because ctr will be first decremented. With the postfix version of these operators, C++ first uses the value of the operand in evaluating the expression before incrementing or decrementing the operand's value. For example, the following code sum = 12; ctr = 4; sum = sum + ctr + + will produce the value of sum as 16 because ctr will be first used in the expression producing the value of sum as 16 and then increment the value of ctr by 1 (ctr becomes now 5) Similary, the following code sum = 12; ctr = 4; sum = sum + ctr - -; will produce the value of sum as 16 because ctr will be first used with its value 4 producing value of sum as 16 and then decrement the value of ctr by 1 (ctr becomes 3). C++ Shorthand Operator Example Equivalent to + = A + = 2 A = A = A - = 2 A = A - 2 % = A % = 2 A = A % 2 /= A/ = 2 A = A / 2 *= A * = 2 A = A * 2

7 - 7 - Conditional operator The conditional operator?: is called ternary operator as it requires three operands. The format of the conditional operator is: Conditional_ expression? expression1 : expression2; If the value of conditional expression is true then the expression1 is evaluated, otherwise expression2 is evaluated.example int a = 5; int b = 6; big = (a > b)? a : b; The condition evaluates to false, therefore big gets the value from b and it becomes 6. The comma operator The comma operator gives left to right evaluation of expressions. It enables to put more than one expression separated by comma on a single line. Example int i = 20, j = 25; int sq = i * i, cube = j * j * j; In the above statements, comma is used as a separator between two statements / expressions. The sizeof operator As we know that different types of Variables, constant, etc. require different amounts of memory to store them The sizeof operator can be used to find how many bytes are required for an object to store in memory. Example sizeof (char) returns 1 sizeof (int) returns 2 sizeof (float) returns 4 If k is integer variable, the sizeof (k) returns 2. the sizeof operator determines the amount of memory required for an object at compile time rather than at run time. The order of Precedence The order in which the operators are used in a. given expression is called the order of precedence. The following table shows the order of precedence: ++, --(post increment/decrement) Highest ++ (Pre increment) --(Pre decrement), sizeof (),!(not),- (unary), +(unary) *,/,% +, - To <, <=, >, >= ==,!= &&?: = Lowest Comma operator LAB EXERCISES - 2 LE 2.1 Write a program to obtain a 4 digit number from the user and display the sum of digits and the reverse number. For example if user enters the number as 1534, the sum should be 13 and reverse number would be LE 2.2 Write a program to obtain seconds form the user and convert and display it into Hours, minutes and numbers format. For example if user inputs seconds as 7295, then your program should display the result as 2 Hours 60 minutes and 35 seconds LE 2.3 Write a program which accepts days as integer and display total number of years, months and days in it. for example : If user input as 856 days the output should be 2 years 4 months 6 days. LE 2.4 Write a program which accepts length1 and length2 in meters and centimeters and display their sum alsi in meter and centimeter form. For example: If user inputs length1 = 10 m 80 cm and length2 = 5 m 60 cm then the output should be 16 m 40 cm. LE 2.5 Write a program which accepts amount as integer and display total number of Notes of Rs. 500, 100, 50, 20, 10, 5 and 1. For example, when user enters a number, 575, the results would be like this : 1 100: 0 50: 1 20: 1 10: 0 5: 1 1: 0

8 - 8 - FLOW OF CONTROL Statements Statements are the instructions given to the computer to perform any kind of action. Action may be in the form of data movement, decision making etc. Statements form the smallest executable unit within a C++ program. Statements are always terminated by semicolon. Compound Statement A compound statement is a grouping of statements in which each individual statement ends with a semi-colon. The group of statements is called block. Compound statements are enclosed between the pair of braces ({.). The opening brace ({) signifies the beginning and closing brace () signifies the end of the block. Null Statement Writing only a semicolon indicates a null statement. Thus ';' is a null or empty statement. This is quite useful when the syntax of the language needs to specify a statement but the logic of the program does not need any statement. This statement is generally used in for and while loops. Conditional Statements Sometimes the program needs to be executed depending upon a particular condition. C++ provides the following statements for implementing the selection control structure. Simple if statement if-else statement Nested if-else statement else if statement switch statement Simple if statement syntax of the if statement if (condition) { statement(s); From the flowchart it is clear that if the if condition is true, statement is executed; otherwise it is skipped. The statement may either be a single or compound statement. if else statement syntax of the if - else statement if (condition) else statement1; statement2; From the above flowchart it is clear that the given condition is evaluated first. If the condition is true, statement1 is executed. If the condition is false, statement2 is executed. It should be kept in mind that statement and statement2 can be single or compound statement. Nested if statement In nested if...else statement, an entire if...else construct is written within either the body of the if statement or the body of an else statement. The syntax is as follows: if (condition_1) { if(condition_2) { block statement_1; else { block statement_2; else { block statement_3; block statement_4;

9 - 9 - else if statement It is used in multi-way decision on several conditions. This works by cascading comparisons. As soon as one of the conditions is true, the statement or block of statements following them is executed and no further comparisons are performed. The else...if syntax is as follows: if(condition_1) block statement_1; else if(condition_2) block statement_2; else if(condition_n) else For example: if (marks > 80) grade = A ; else if (marks > 60) grade = B ; block statement_n; else if (marks > 40) else default statement; grade = C ; grade = D LAB EXERCISES - 3 LE 3.1 Write a program to check whether the given number is even or odd (using?: ternary operator ). LE 3.2 Write a program to check whether the given number is positive or negative (using?: ternary operator ). LE 3.3 Write a program to find the greatest of three unequal numbers (using? : ternary operator ). LE 3.4 Write a program to find the grade based on marks (using? : ternary operator ). LE 3.5 Write a program to find the electricity bill based on units consumed (using? : ternary operator ). LE 3.6 Write a program to find the income tax (using?: ternary operator ). LE 3.7 Write a program to find the gain or loss% (using?: ternary operator ). LE 3.8 Write a program to find the nature and roots of a quadratic equation (using?: ternary operator ). LE 3.9 Write a program to find slant height, LSA,TSA, Volume of two cones and compare them (using? : ternary operator ). LE 3.10 Write all the above programs using if else statement.

10 LE 4.01 LE 4.02 LE 4.03 LE 4.04 LE 4.05 LE 4.06 LE 4.07 LE 4.08 LE 4.09 LE 4.10 LE 4.11 LE 4.12 LAB EXERCISE 4 (USE IF.ELSE) Any integer is input by the user. Write a program to find out whether it is an odd number or even number. Find the absolute value of a number entered by the user. Write a program to calculate the total expenses. Quantity and price per item are input by the user and discount of 10% is offered if the expense is more than Write a program to determine whether the seller has made profit or incurred loss. Also determine how much profit he made or loss he incurred. Cost price and selling price of an item is input by the user. If the ages of Ram, Sulabh and Ajay are input by the user, write a program to determine the youngest of the three. Write a program to check whether a triangle is valid or not, when the three angles of the triangle are entered by the user. A triangle is valid if the sum of all the three angles is equal to 180 degrees. Any year is input by the user. Write a program to determine whether the year is a leap year or not. In a company an employee is paid as under: If his basic salary is less than Rs. 1500, then HRA = 10% of basic salary and DA = 90% of basic salary. If his salary is either equal to or above Rs. 1500, then HRA = Rs. 500 and DA = 98% of basic salary. If the employee's salary is input by the user write a program to find his gross salary. Write a program to calculate the monthly telephone bills as per the following rule: Minimum Rs. 200 for upto 100 calls. Plus Rs per call for next 50 calls. Plus Rs per call for next 50 calls. Plus Rs per call for any call beyond 200 calls. Write a program to find the roots of and quadratic equation of type ax2+bx+c where a is not equal to zero. The marks obtained by a student in 5 different subjects are input by the user. The student gets a division as per the following rules: Percentage above or equal to 60 - First division Percentage between 50 and 59 - Second division Percentage between 40 and 49 - Third division Percentage less than 40 - Fail Write a program to calculate the division obtained by the student. Any character is entered by the user; write a program to determine whether the character entered is a capital letter, a small case letter, a digit or a special symbol. The following table shows the range of ASCII values for various characters. Characters ASCII Values A Z a z special 0-47, 58-64, 91-96, symbols