C++ Input/Output Operator | cout and cin | My CS Tutorial

C++ Input/Output | cout and cin | cascading of input and output operators | I/O operator in c++

C++ uses a convenient abstraction called streams to perform input and output operations in sequential media such as the screen or the keyboard. A stream is an object where a program can either insert or extract characters to/from it.

The standard C++ library includes the header file iostream, where the standard input and output stream objects are declared.

C++ i/o operations | My CS Tutorial

STANDARD OUTPUT(cout)

By default, the standard output of a program is the screen, and the C++ stream object defined to access it is cout.

cout is used in conjunction with the insertion operator, which is written as << (two "less than" signs).

Example:-

cout << "Output sentence";
// prints Output sentence on screen

cout << 120;
 // prints number 120 on screen

cout << x;
// prints the content of x on screen

The insertion operator (<<) may be used more than once in a single statement:-

cout << "Hello, " << "I am " << "a C++ statement";

This last statement would print the message Hello, I am a C++ statement on the screen. The utility of repeating the insertion operator (<<) is demonstrated when we want to print out a combination of variables and constants or more than one variable:-

cout << "Hello, I am " << age << " years old and my zipcode is " << zipcode;


If we assume the age variable to contain the value 24 and the zipcode variable to contain 90064 the output of the previous statement would be:-
output:-

Hello, I am 24 years old and my zipcode is 90064

STANDARD INPUT(cin)

The standard input device is usually the keyboard. Handling the standard input in C++ is done by applying the overloaded operator of extraction (>>) on the cin stream. The operator must be followed by the variable that will store the data that is going to be extracted from the stream. For example:-

int age;

cin >> age;


The first statement declares a variable of type int called age, and the second one waits for an input from cin (the keyboard) in order to store it in this integer variable.

Example:-

// i/o example

#include <iostream>

using namespace std;

int main ()

{

 int i;

 cout << "Please enter an integer value: ";

 cin >> i;

 cout << "The value you entered is " << i;

 cout << " and its double is " << i*2 << ".\n";

 return 0;

}


Please enter an integer value: 500

The value you entered is 500 and its double is 1000.

You can also use cin to request more than one datum input from the user:-

cin >> a >> b;

is equivalent to:-

cin >> a;

cin >> b;


In both cases the user must give two data, one for variable a and another one for variable b that may be separated by any valid blank separator: a space, a tab character or a newline.

CASCADING OF INPUT/OUTPUT OPERATOR:-

using the cascating techniques,two statement can be combined as follows:-

cout<<"Sum="<<sum<<"\n"
      <<"Average="<<avg<<"\n";
   
 This is one statement by provides two lines of output like:-

 Sum = 5
 Average = 2.5

 If you want only one line of output as given below:-

 Sum = 5  Average = 2.5

 cout<<"Sum="<<sum<<",""
       <<"Average="<<avg<<"\n";
     

C++ Input/Output | cout and cin | cascading of input and output operators | I/O operator in c++

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Created by-- HARSH CHAUHAN