Input and Output in C++
Output in C++:
Output in C Plus Plus (C++) is enabled by the object
cout (pronounced as “C out”) which is predefined to corresponding to the standard output stream. A stream is an abstraction that refers to a flow of data. The standard output stream normally flows to the screen display, although it can be redirected to other output devices.
cout, when combined with insertion or put-to operator
<< enables the output in C++ programs.
<< operator redirects the contents of the variable on its (<<‘s) right to the object on its(<<‘s) left.
A simple example of output of a phrase is depicted below:
cout << "LearnCppOnline.com is the best C++ programming tutorial site";
Above statement causes the phrase in the quotation marks to be displayed on the screen.
Input in C++
cout, to receive input through the keyboard what is used is object
cin (pronounced as “C in”).
cin is a object predefined in C++ to correspond to the standard input stream. This stream represents the data coming from the keyboard (unless it has been redirected).
cin, when combined with extraction or get-from operator
>> enables the input in C++ programs.
>> operators takes the value from the object on its (
>>‘s) left and places it in the variables on its right.
A simple example of input of the value of a single variable is depicted below:
cin >> n;
Above statement causes the value provided from the keyboard to get assigned to the variable n.
Cascading of Input and Output in C++
Cascading of input and output is also possible in C++, Let us illustrate this with the following examples:
Example depicting cascading of Input
Suppose we want to read the values from the variables n1, n2 and n3. We can do this with the single statement:
cin >> n1 >> n2 >> n3;
Above one statement is equivalent to the following three statements:
cin >> n1; cin >> n2; cin >> n3;
Example depicting cascading of Output
Suppose we want to print the values of the variables n1 and n2. We can do this with the single statement:
cout << "n1 = " << n1 << "n2 = " << n2;
Above one statement is equivalent to the following four statements:
cout << "n1 = "; cout << n1; cout << "n2 = "; cout << n2;
A Special Mention of Header File required for Input and Output in C++
To enable the use of
>>, one needs to include a header file named
iostream.h in the first line of every program, by the statement:
This header file contains the declaration that are needed by
cin objects and
>> operators. Without this declaration, the compiler won’t recognize
cin and will think
>> are being used incorrectly in the program.