May 27, 2017 The two keywords cout in C and cin in C are used very often for printing outputs and taking inputs respectively. These two are the most basic methods of taking input and printing output in C. To use cin and cout in C one must include the header file iostream in the program.
-->Declares objects that control reading from and writing to the standard streams. This include is often the only header you need to do input and output from a C++ program.
- The cout object in C is an object of class ostream. It is used to display the output to the standard output device i.e. It is associated with the standard C output stream stdout.
- May 30, 2013 Hmm I'm still fairly new to c myself only 3 weeks in and I haven't had to use that header for my programs yet. With problem 2 your are typing a meal out but what you are telling your program with int is that you would input a whole number value.
Syntax
Note
The <iostream> library uses the
#include <ios>
, #include <streambuf>
, #include <istream>
, and #include <ostream>
statements.Remarks
The objects fall into two groups:
- cin, cout, cerr, and clog are byte oriented, doing conventional byte-at-a-time transfers.
- wcin, wcout, wcerr, and wclog are wide oriented, translating to and from the wide characters that the program manipulates internally.
Once you do certain operations on a stream, such as the standard input, you can't do operations of a different orientation on the same stream. Therefore, a program can't operate interchangeably on both cin and wcin, for example.
All the objects declared in this header share a peculiar property — you can assume they're constructed before any static objects you define, in a translation unit that includes <iostream>. Equally, you can assume that these objects aren't destroyed before the destructors for any such static objects you define. (The output streams are, however, flushed during program termination.) Therefore, you can safely read from or write to the standard streams before program startup and after program termination.
This guarantee isn't universal, however. A static constructor may call a function in another translation unit. The called function can't assume that the objects declared in this header have been constructed, given the uncertain order in which translation units participate in static construction. To use these objects in such a context, you must first construct an object of class ios_base::Init.
Global Stream Objects
cerr | Specifies the cerr global stream. |
cin | Specifies the cin global stream. |
clog | Specifies the clog global stream. |
cout | Specifies the cout global stream. |
wcerr | Specifies the wcerr global stream. |
wcin | Specifies the wcin global stream. |
wclog | Specifies the wclog global stream. |
wcout | Specifies the wcout global stream. |
cerr
The object
cerr
controls output to a stream buffer associated with the object stderr
, declared in <cstdio>.Return Value
An ostream object.
Remarks
The object controls unbuffered insertions to the standard error output as a byte stream. Once the object is constructed, the expression
cerr.
flags&
unitbuf is nonzero, and cerr.tie() &cout
.Example
cin
Specifies the
cin
global stream.Return Value
An istream object.
Remarks
The object controls extractions from the standard input as a byte stream. Once the object is constructed, the call
cin.
tie returns &
cout.Example
In this example,
cin
sets the fail bit on the stream when it comes across non-numeric characters. The program clears the fail bit and strips the invalid character from the stream to continue.clog
Specifies the
clog
global stream.Return Value
An ostream object.
Remarks
The object controls buffered insertions to the standard error output as a byte stream.
Example
See cerr for an example of using
clog
.cout
Specifies the
cout
global stream.How To Use Cout
Return Value
An ostream object.
Remarks
The object controls insertions to the standard output as a byte stream.
Example
See cerr for an example of using
cout
.wcerr
Specifies the
wcerr
global stream.Return Value
A wostream object.
Remarks
The object controls unbuffered insertions to the standard error output as a wide stream. Once the object is constructed, the expression
wcerr.
flags&
unitbuf is nonzero.Example
See cerr for an example of using
wcerr
.wcin
Specifies the
wcin
global stream.Return Value
A wistream object.
Remarks
The object controls extractions from the standard input as a wide stream. Once the object is constructed, the call
wcin.
tie returns &
wcout.Example
See cerr for an example of using
wcin
.wclog
Specifies the
wclog
global stream.Return Value
A wostream object.
Remarks
The object controls buffered insertions to the standard error output as a wide stream.
Example
See cerr for an example of using
wclog
.wcout
Specifies the
wcout
global stream.Return Value
A wostream object.
Remarks
The object controls insertions to the standard output as a wide stream.
Example
See cerr for an example of using
wcout
.CString
instances in a wcout
statement must be cast to const wchar_t*
, as shown in the following example.For more information, see Basic CString Operations.
See also
Header Files Reference
Thread Safety in the C++ Standard Library
iostream Programming
iostreams Conventions
Thread Safety in the C++ Standard Library
iostream Programming
iostreams Conventions