Basic Features of c
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Transcript of Basic Features of c
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BASIC FEATURES OF C++
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Characters and character set
The characters used in the C++ program are
upper and lower case letters, A to Z and a to z
digits 0 to 9
the space character
control characters- new line, horizontal andvertical tab, form feed, bell
special characters (or symbols)
_ { } [ ] # ( ) < > $ : ; . ? * + -/ ^ & | ~ ! = , \ " '
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Variable
A variable is a name given to a memorylocation where you can store a data of a
particular type. The type is specified when thevariable is declared.
The name you can give to a variable canconsist of any combination of upper or lowercase letters, underscores ( _ ) and the digits (
0 to 9 ).
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A variable name is case sensitive. (C++ is acase sensitive language). This means length
and Length, LENGTH are different names.
A variable name cannot begin with a digit.
Examples of variable names:
monthly_salary, temperature, pay, mark,mark_ce204,
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Declaration of Variable
Examples of variable declaration:
int student_no;
int age;
int student_no, age;
string name;
double length, width, area;
int count=0;
int a=5, b=2;
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Basic data types
char
short
int
long
float
double
long double
string
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There are also type such as unsignedlong, unsigned short, unsigned intsigned long, signed short, signed int.
Typically float will provide 7 digitprecision, double will provide 15 digit
precision and long double will provide19 digit precision
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Keywords
These are reserved words that have particularsignificance and when needed are to be used
as it is. In the above program include,iostream, using, namespace, std, int, cout,return are keywords.
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blocks
A statement is analogous to a sentencein any language.
A C++ statement expresses a completeinstruction to the computer. Statementsare basic units for specifying what our
program is to do.
Most C++ statements end with a
semicolon.
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Examples of C++ statement andstatement block:
#include
double result; //declaration
double result=0.0; //declaration and initialization
length = 5.0; // assignment
if(marks>=40)
cout
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Whitespace
Whitespace refers to spaces, horizontal andvertical tabs and newline characters.Whitespaces are required in a C++ statement forthe compiler to be able to distinguish between the
elements of the statement.
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Function, function name and
function body
A function is a self-contained block of codereferenced by a name. There may be morethan one function in a C++ program, but there
shall be at least one function named mainandnot more than one function shall have thename main.
The brackets ( ) after the function name isessential. A function may have arguments thatare placed within these brackets.
The function has a type.
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directive
#include includes the contents of theheader file iostream into the program.
iostream is one of several standard header files thatare supplied with C++ compiler.
The header files contain information (code) for theavailable library functions. The name cout is defined inthe header file iostream. This is a standard header filethat provides the definitions necessary for standardinput and output facilities. The standard input device isthe keyboard and the standard output device is themonitor.
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Namespace
The namespace refers to a group of severalnames (or entities). The entities in the C++standard library are all defined within anamespace called std. You may also consider
namespace as a surname. You may consider thatthe full name ofcout is std::cout. If we omit theusing directive we can write the output statementas
std::cout
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Returnstatement The return statement ends the function and
returns control to the operating system. It alsoreturns a value (0 in the above example) to theoperating system.
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EXAMPLE
/* Program that finds the average
of two numbers */
#include
using namespace std;
int main()
{
double num1, num2, average;
cout