X=2 and Y = 3 What Would Cin >> X >> Y; Read?

Basics of C/C++ Programming

Writing simple C++ programs

Example 1

//  Simple printing lawmaking.  #include <iostream> using namespace std;  int main() { 	int a = 10, b = 20; 	     cout << "sum is" << a + b << endl; 	cout << "product is " << a*b << endl;  	return 0; }          

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A typical c++ program uses several header files in order to use the library routines that has been developed already. In the above example, the argument #include <iostream> indicates that we need the I/O library. The statement "#using namespace std;" says that this example use output operator "<<" defined in the standard proper name space. In this example, a user has declared two integers a and b; and, they are initialized to x and 20 respectively. Finally it computes the sum and products of a and b and outputs them on the console as shown below.

Example two

//  Simple printing lawmaking. //  #include <iostream> using namespace std;  int master() { 	int a, b; 	cout << "Input a:"; cin >> a; 	     cout << "Input b:"; cin >> b; 	     cout << "sum is" << a + b << endl; 	     cout << "product is " << a*b << endl;  	return 0; }          

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This example is very like to the previous i except that the user inputs the values "a" and "b" and they are read using the input operator "cin". Finally the lawmaking calculates and prints the values of the sum and product of a and b

Data types

Computer stores the variables in the memory. Therefore, computer needs to know what kind of information nosotros store and then that computer reserves some memory space for the variable. A Byte [B] is the minimum corporeality of memory infinite for a computer. One Byte is eight bits and a bit is either 0 or 1. 1KB=2^8=1024 Bytes Information type is defined as a fix of values together with a set up of operations. C++ information types may be grouped into three categories:

Uncomplicated

Structured

Arrow

Simple Information Types:

There are iii categories within the uncomplicated information type

1. Integral: integer (Whole numbers)
2. Floating-point: Real numbers
3. Enumeration blazon: user-defined data type
4. Of import Variants integral data types are
1. int
2. bool
3. Char

It is also the number of bytes taken by a data type is compiler dependent. short or short int data type covers whole numbers that tin be positive or negative (-128 to 127). unsigned brusque int takes just positive number (0 to 255)

Examples:

• -6728
• 0
• 78
• +763
• P78
1. Annotation that + sign is optional
2. No commas should be used within an integer (east.yard. ten.825 is wrong)

In order to utilize a variable in C++, the variables should be declared first with the types.

Instance.i

Following program has int a, b, and c. a and b values are given and find c. Prints a, b, and c

#include <iostream>  using namespace std;   int main()   { 	int a=ten, b=5, c; 	    c = a*b; 	        cout << "a = " << a <<", b= "<<b<<endl;  	cout << "c = " << c << endl;  	return 0; }          

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Instance.1:

Following program has int a, b, and c. user tin enter a and b values and calculate c. Prints a, b, and c

            #include <iostream>  using namespace std;   int main()   { 	int a, b, c;  	cout<<"Enter integer a and b values :";  	cin>>a>>b; 	c = a*b;  	cout << "a = " << a <<", b= "<<b<<endl;  	cout << "c = " << c << endl;  	return 0; }          

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It is proficient habit to have prompt earlier cin command and so that user knows that he has to reply.

bool Data Type

bool type

• Two values: true and false
• Manipulate logical (Boolean) expressions

true and false are called logical values

bool, true, and false are reserved words

char Data Type

The smallest integral data type

Used for characters: messages, digits, and special symbols

Each character is enclosed in single quotes

• 'A', 'a', '0', '*', '+', '$', '&'

A bare space is a graphic symbol and is written ' ', with a space left betwixt the single quotes

Case

#include <iostream>  using namespace std;   int main()   { 	char x1='C';  	char x2='P';  	cout<<" This is a exam..."<<endl;  	cout<<"Answer : "<<x1<<x2<<x2<<endl;  	render 0; }        

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Result

Instance

It is proficient habit to have prompt before cin control so that user knows that he has to respond.

#include <iostream>  using namespace std;   int chief()   { 	char x1='C', x2='P';  	cout<<" This is a examination..."<<endl;  	cout<<" Respond : "<<x1<<x2<<x2<<endl;  	cout<<endl;   	return 0; }        

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Example

#include <iostream>  using namespace std;   int main()   { 	char x1, x2;  	cout<<" Enter x1 and x2 chacaters:";  	cin>>x1>>x2;  	cout<<" This is a test..."<<endl;  	cout<<" Answer : "<<x1<<x2<<x2<<endl;  	cout<<endl;    return 0;  }        

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Event

Existent Numbers

1. C++ uses scientific annotation to represent real numbers (floating-bespeak notation or scientific note)
2. This allows a user to represent likewise small and besides large numbers
1. iii.141592
2. 0.3679
3. 1.602e-19
4. 3.4e+64 ( 50! Fifty factorial)
5. 1.2e9 (i.2 GHz)
3. Real numbers may exist classified as bladder and double

[We always utilize double in our code as it is more than accurate than float]

Example

#include <iostream>  using namespace std;   int chief()   { 	double x1, x2;  	cout<<" Enter x1 and x2 double numbers:";  	cin>>x1>>x2;  	cout<<" This is a test..."<<endl;  	cout<<" Total : "<< x1 <<" + "<< x2 <<" = "<< x1+x2 << endl;  	cout<<endl;    render 0; }        

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Outcome

Case

#include <iostream>  using namespace std;   int main()   { 	double x1, x2, full;  	cout<<" Enter x1 and x2 double numbers:";  	cin>>x1>>x2; 	full=x1+x2;  	cout<<endl;  	cout<<" Total : "<< x1 <<" + "<< x2 <<" = "<< full << endl;  	cout<<endl;    return 0; }        

Consequence

Enumerated data types allows to designate a symbolic name for each integer.

This method Improves readability of your lawmaking

Examples

enum direction {North, Due south, East, West};

// Here North=0, South =1, East =2, and W =3

enum radixchoice {binary, octal, decimal, hex};

Now 1 define a variable effectually this enumerated blazon direction myheading = East; radixchoice mybase=hex;

Variables

Variable is a location in memory where a value can be stored. Declare variables with data type and name before employ

Example int x1; int x2; int sum;

You tin declare several variables of same type in 1 declaration Comma separated list

int x1, x2, sum;

Variable proper noun must be a valid identifier

Serial of characters (letters, digits, underscores)

Cannot begin with digit

Example sensitive (uppercase messages are different from lowercase letters)

Utilize identifiers of 31 characters or fewer

Avoid identifiers that begin with underscores and double underscores, because C++ compilers may use names like that for their ain purposes internally

At that place are some reserved keywords for C++, avoid using them as variable names.

Information technology is ameliorate to identify a infinite later each comma (,) to make programs more readable. If you like you tin can declare each variable on a dissever line. And then that you to place a comment next to each declaration

Information technology is better to place declarations at the first of a office and split up them from the executable statements with 1 blank line to highlight where the declarations end and the executable statements begin

The post-obit list shows the some reserved words in C++. These reserved words may not be used as constant or variable or any other identifier names.

Instance

          #include <iostream>  using namespace std;   int master()   { 	double x1, x2, total;  	cout<<" Enter x1 and x2 double numbers:";  	cin>>x1>>x2; 	total=x1+x2;  	cout<<endl;  	cout<<" Full : "<< x1 <<" + "<< x2 <<" = "<< full << endl;  	cout<<endl;    render 0; }        

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Global Variables:

Global variables are defined outside of all the functions, usually on top of the program. The global variables are available for use the entire program afterwards the declaration and can exist accessed by whatever part in the program. Following are some examples using global and local variables:

Example

#include <iostream>  using namespace std;  // Global variable declaration: int Y;   int main ()   {  	// Local variable annunciation:   	int a, b; // actual initialization   	a =10;   	b =xx;   	Y = a + b;   	cout <<"The full is :"<< Y<<endl;     return 0; }        

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Result

Note:Note: If a programme can have aforementioned name for local and global variables, the value of local variable inside a function volition take preference.

Example

#include <iostream>  using namespace std;   // Global variable declaration:   int Y;   int main ()   {  	// Local variable announcement and nitialization :   	int a=x, b=20,Y=30;  	      Y = a + b + Y;   	cout <<"The total is :"<< Y << endl;    return 0; }        

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Result

Operators:

Operators tells the compiler to perform specific mathematical or logical operations. C++ has following built-in operators:

Arithmetic Operators

Relational Operators

Logical Operators

Bitwise Operators

Assignment Operators

Arithmetic Operators:The following arithmetic operators supported by C++ linguistic communication:

The increase operator ++ adds 1 to its operand, and the decrement operator -- subtracts 1 from its operand

Example:

Case x = x+one; can be written as x++; //postfix class

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Source: https://www.cpp.edu/~elab/ECE114/Basic-of-C++.html

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