C++ PROGRAMMING BASICS

 Submitted By Amir Hayat
 Submitted To Sir Imran

1. Functions
• Whitespace
1. Output Using cout
2. String Constants
3. Directives
4. Preprocessor Directives
5. Header Files
6. The using Directive
7. Comments
8. Comment Syntax
12. Alternative Comment Syntax
13. Integer Variables Defining
14. Integer Variables
15. Declarations and Definitions
16. Variable Names
17. Assignment Statements
18. Integer Constants
19. Output Variations
20. The endl Manipulator

21. Other Integer Types
22. Character Variables
23. Character Constants
24. Initialization
25. Escape Sequences
26. Input with cin
27. Cascading <<
28. Expressions
29. Precedence
30. Floating Point Types
31. Type float
32. Type double and long double
33. Floating-Point Constants
34. The constant Qualifier
35. The #define Directive
36. Type bool
37. The setw Manipulator
38. Cascading the Insertion Operator
39. Multiple Definitions
40. The IOMANIP Header File
41. Variable Type Summary
42. unsigned Data Types
43. Type Conversion
44. Automatic Conversions
45. Casts
46. Arithmetic Operators
47. The Remainder Operator
48. Arithmetic Assignment Operators
49. Increment Operators
50. Library Functions
51. Header Files
52. Library Files
53. Header Files and Library Files
54. Two Ways to Use #include

The Large Number of Program is Divided in Small Pieces and Each Part
Perform a Special Function
Example :
• Main()
• Printf()

The compiler ignores whitespace almost
completely.

cout << “Aami Kakakhel”;
The Text in quotation marks is to be displayed on the screen. The identifier
cout (pronounced “C out”) is actually an object. It is predefined in C++ to
correspond to the standard output stream
The operator << is called the insertion or put to operator.
it directs the string constant “Aami Kakakhel” to cout, which sends it to the
display.

The text in quotation marks, “Aami Kakakhel”, is an example of a string
constant. As you probably know, a constant, unlike a variable, cannot be given
a new value as the program runs. Its value is set when the program is written,
and it retains this value throughout the program’s existence. As we’ll see later,
the situation regarding strings is rather complicated in C++. Two ways of
handling strings are commonly used. A string can be represented by an array
of characters, or it can be represented as an object of a class. “Arrays and
Strings

The first two lines that begin the program are directives. The first
is a preprocessor directive, and the second is a using directive.
They’re not part of the basic C++ language, but they’re necessary
anyway.

The first line of the program,
#include <iostream>
might look like a program statement, but it’s not. It isn’t part of a function body
and doesn’t end with a semicolon, as program statements must. Instead, it starts
with a number sign (#). It’s called a preprocessor directive
The preprocessor directive #include tells the compiler to insert another file into your
source file

The preprocessor directive #include tells the compiler to add the source
file IOSTREAM to the source file before compiling
IOSTREAM is an example of a header file (sometimes called an include
file)
Example:
Header Files
Execute

A C++ program can be divided into different namespaces. A namespace is a
part of the program in which certain names are recognized; outside of the
namespace they’re unknown. The directive
using namespace std; says that all the program statements that follow are
within the std namespace. Various program components such as cout are
declared within this namespace

Comments are an important part of any program. They help the person
writing a program, and anyone else who must read the source file,
understand what’s going on. The compiler ignores comments, so they
do not add to the file size or execution time of the executable program

//Aami kakakhel
Comments start with a double slash symbol (//)
and terminate at the end of the line.

Comments are used for explain Source Code of A Programmer.
Or Explain Each Statement Of Source Code .

/* this is an old-style comment */
begins with the /* character pair and ends with */ (not with the end of the line)
this style is not generally used in C++. However
/* Alternative
Comment Is Written
In Many Line's like this */

Variable Mean Which Chang At time of execution.
Integer variables represent integer numbers Like 420 302 2016 etc
Integer Variables Have No fractional part
Example:
Source Program
Execute

Int x;
You must declare a variable before using it. However, you can place variable
declarations anywhere in a program. It’s not necessary to declare variables before the
first executable statement (as was necessary in C).
Example:
Source Program
Execute

A declaration introduces a variable’s name (such as var1) into a program
and specifies its type (such as int ). However, if a declaration also sets
aside memory for the variable, it is also called a definition
Example:
Source Program
Execute

The names given to variables (and other program features) are called identifiers
can use upper- and lowercase letters, and the digits from 1 to 9. You can also use the underscore (_).
The first character must be a letter or underscore. Identifiers can be as long as you like, but only the
first 247 characters (in Visual C++) or 250 characters (in C++ Builder) will be recognized. The
compiler distinguishes between upperand lowercase letters, so Var is not the same as var or VAR.

var1 = 20;
var2 = var1 + 10;
Assign values to the two variables. The equal sign =, as you might guess, causes
the value on the right to be assigned to the variable on the left. The = in C++ is
equivalent to the := in Pascal or the = in BASIC. In the first line shown here,
var1, which previously had no value, is given the value 20.

The number 20 is an integer constant. Constants don’t change
during the course of the program. An integer constant consists of
numerical digits. There must be no decimal point in an integer
constant, and it must lie within the range of integers

cout and the << operator know how to treat an integer
and a string differently. If we send them a string, they
print it as text. If we send them an integer, they print
Value Save In Integer Variable

Cout<<endl;
endl Manipulator is Used in Output for new line in C++.and In C
language We use /n in place of endl

Type char stores integers that range in value from –128 to 127. Variables
of this type occupy only 1 byte (eight bits) of memory. Character
variables are sometimes used to store numbers that confine themselves
to this limited range, but they are much more commonly used to store
ASCII characters

Character constants use single quotation marks around a character, like ‘a’ and
‘b’. (Note that this differs from string constants, which use double quotation
marks.)
When the C++ compiler encounters such a character constant, it translates it
into the corresponding ASCII code. The constant ‘a’ appearing in a program,
for example, will be translated into 97

Variables can be initialized at the same time
they are defined

The name reflects the fact that the backslash causes an “escape” from
the normal way characters are interpreted
Value Escape sequence
newline n
horizontal tab t
vertical tab v
backspace b
carriage return r
form feed f

Cin>>t;
The program to wait for the user to type in a number. The resulting
number is placed in the variable t.
Example:
Source Program
Execute

If we want to print some things in same time so we just us << and Write cout
just one time in same statement like
Cout<<“aami”<<abc;

Any arrangement of variables, constants, and operators that specifies a
computation is called an expression
When the Calculation is done in Expression so Value Become in Output
Example:
Source Program
Execute

All Parentheses are evaluate first
Multiplying, Division, and Modulus is 2nd But each have same level of
precedence if any expiration have each of then so calculate from lift to wright
At least addition and subtraction is also same level.
Example:
Source Program
Execute

Floating-point variables represent numbers with a decimal place—like
3.1415927, 0.0000625, and –10.2. They have both an integer part, to the
left of the decimal point, and a fractional part
Example:
Source Program
Execute

Type float stores numbers in the range of about 3.4×10–38 to 3.4×1038,
with a precision of seven digits
Example:
Source Program
Execute

The larger floating point types, double and long double, are similar to
float except that they require more memory space and provide a wider
range of values and more precision

The number 3.14159F in CIRCAREA is an example of a floating-point
constant. The decimal point signals that it is a floating-point constant, and
not an integer, and the F specifies that’s it’s type float, rather than double or
long double
Example:
Source Program
Execute

const float PI = 3.14159F;
float The keyword const (for constant) precedes the data type of a variable. It
specifies that the value of a variable will not change throughout the program

This directive sets up an equivalence between an identifier and a text phrase.
For example, the line
#define PI 3.14159
appearing at the beginning of your program specifies that the identifier PI will
be replaced by the text 3.14159 throughout the program. This construction has

Variables of type bool can have only two possible values: true and false.
In theory a bool type requires only one bit (not byte) of storage

We’ve mentioned that manipulators are operators used with the insertion
operator << to modify—or manipulate—the way data is displayed. We’ve
already seen the endl manipulator; now we’ll look at another one: setw, which
changes the field width of output.
Example:
Source Program
Execute

Variable Mean Which Chang At time of
execution.
Integer variables represent integer numbers
Like 420 302 2016 etc
Integer Variables Have No fractional part
Example:
Source Program
Execute

Int a,b,c;
We initialized the variables a, b, and c to specific values at the
same time we defined them
the same int keyword and separating the variable names with
commas. This saves space where a number of variables are all the
same type.

Keyword Low High Precision Memory
char –128 127 n/a 1
short –32,768 32,767 n/a 2
int –
2,147,483,648 2,147,483,647
n/a 4
long –
2,147,483,648
2,147,483,647 n/a 4
float 3.4 x 10–38 3.4 x 1038 7 4
double 1.7 x 10–308 1.7 x 10308 15 8
long double 3.4 x 10–4932 1.1 x 104932 19 10

Their range to start at 0 and include only positive numbers.
Example:
Source Program
Execute

When two operands of different types are encountered in the same
expression, the lower-type variable is converted to the type of the
higher-type variable.
Example:
Source Program
Execute

In case if calculation is an among the to different data type like float
and integer so the integer convert into temporary variable of type float
for calculation ta a time of calculation
Example:
Source Program
Execute

Sometimes a programmer needs to convert a value from one type to
another in a situation where the compiler will not do it automatically
or without complaining.
Example:
Source Program
Execute

C++ uses the four normal arithmetic operators +, -, *, and / for
addition, subtraction, multiplication, and division. These operators
work on all the data types, both integer and floating-point.
Example:
Source Program
Execute

There is a fifth arithmetic operator that works only with integer variables (types char,
short, int, and long). It’ s called the remainder operator, and is represented by %, the
percent symbol. This operator (also called the modulus operator) finds the
remainder when one number is divided by another. The REMAIND program
demonstrates the effect.
Example:
Source Program
Execute

There are arithmetic assignment operators +=, -=, *=, /=, and %= (and
some other operators as well)
Example:
Source Program
Execute

A++; = A=A+1;
++A
Prefix mean first execute then change it.
A++
Postfix mean first change then execute.
Example:
Source Program
Execute

There are a number of library function available in C/C++ Language that perform trigonometrically arithmetical and string
operations automatically.
These functions make programming muchsimpler in many situationsand save the Programmer’sEffort
The C language is accompaniedby a number of standard libraryfunctionswhich carryout various useful tasks. In particular,all
input and output operations (e.g., writing to the terminal) and all math operations (e.g., evaluation of sines and cosines) are
implemented bylibraryfunctions.
Example:
SOME EXAMPLES

A headerfileis a file with extension .h which contains C function declarations
and macro definitions to be shared between several source files. There are two
types of headerfiles: the filesthat the programmer writes and the filesthat
comes with your compiler.
Example:
Source Program
Execute

In programming, a library is a collection of precompiled routines that a program
can use. The routines, sometimes called modules, are stored in object format .
Libraries are particularly useful for storing frequently used routines because you
do not need to explicitly link them to every program that uses them
Example:
Source Program
Execute

C++ PROGRAMMING BASICS

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