Statements in C++

An executable instruction is known as a statement. They can classified into two main categories:

1. Simple statements or expression statements.
2. Complex statements(Control statements: next chapter).

1) Expression Statements:

Any expression ending with a semi-colon (;) is known as an expression statement. For e.g.:

• a=b;
  
• A=5;
  
• a=b+c;
  
• a++;
  

Input statement:

'cin' is an object(variable) declared in 'iostream.h' header file that represents the standard input device i.e. keyboard. This variable together with >> (extraction operator here) can be used for reading the value of a variable from the keyboard.
Syntax:

cin>>variable_name; --> this is an expression.
cin>>variable_name; --> this is a statement known as input statement.

e.g.
int a;
cin>>a; //to read value of a

General syntax:
cin>>variable1>> variable2>>...>> variable.

Constants:

In C++ constants are classified into two categories:
1) Numeric constants:
2, 5, -45, 1.1245, 1.542e+4, etc.
2) Non-numeric constants:

1. Character constants --> Any character within ' ' is a character constant.
E.g.: 'A', 'b', '6', '+'.


2. String constants --> Any sequence of characters within " " is known as a string.
E.g.: "Hello world", "12+152".

Output statement:

'cout' is an object that represents the standard output device i.e. monitor. Using cout together with << (insertion operator here), we can display the value of a variable or a constant or an expression.
Syntax:
cout< This is an expression.
cout< This is a statement known as output statement.

1. cout<<"hello";
   output --> hello
   
   
2. cout<<"Hello";
   cout<<"Hello";
   output --> HelloHello
   
   
3. cout <<"Hello\n";
   cout<<"Hello"
   output-->Hello
   Hello
   
   Note -->'\n' is a special character constant known as new line character that brings the cursor to the next line.
   
   
4. Let a=5, b=6
   cout << a;
   cout << b;
   output --> 56
   
   
5. cout<<"Value of a= " << a;
   cout<<"Value of b= " << b;
   output --> Value of a= 5Value of b= 6
   
   

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