A console program is one that can be written using only functions and
language features that are compatible with the C or C++ standard. If a program
uses the standard exclusively, then it can be compiled for any operating system
that has a compiler for the standard. This is can be very important. It is
therefore very useful to be familiar with the standard. I think that functions
such as "cout" are a separate standard but whether they are part of the C++
standard or are a separate standard, they are worth knowing. There are actually
two types of console programs; 16-bit and 32-bit. A 16-bit program is a true DOS
program. A 32-bit console program is a Windows program that can be compatible
with other operating systems at the source code level if it does not have any
direct calls to Windows.
A console application is not a Windows GUI application. Something to
understand that is highly relevant is that according to the C and C++ standard
all programs have a "main" function. A Windows GUI application has a "WinMain"
function instead of a "main" function; 16-bit DOS programs and 32-bit console
programs have a "main" function. Also Windows GUI applications can be either
16-bit or 32-bit.
16-Bit DOS Applications
A 16-Bit DOS application uses DOS functions but cannot call Windows functions
directly. DOS is called using software interrupts, which is a processor
instruction. Software interrupts are prohibited in 32-bit Windows programs.
32-Bit Console Applications
A 32-Bit console application cannot issue a software interrupt and therefore
cannot call DOS directly. A 32-Bit console application calls Windows directly
for most anything that DOS would be used for. Often a 32-Bit console application
relies entirely on C runtime library functions and/or the C++ Standard Classes
and other features within the standards. There are also extensions to the
standards that are compiler-dependent that can be used without using Windows
directly. However those functions call Windows but not DOS.
Windows GUI Applications
A Windows GUI program is not compatible with the C++ standard; that is, a
Windows GUI program
will only work in a Windows environment. A GUI program however
can use Windows windows easier than a console program can. Most Windows programmers
would say that a GUI program is a "Windows" program whereas a console program is
not, but I am not aware of Microsoft saying that.
I am simplifying things to make it easier to understand, but the truth is that a
console program can do most everything a GUI program can do and a GUI program
can do most everything a console program can do; it is just a matter of knowing
how to do them. If anyone were to try to explain the differences between the two
types and still be totally accurate about what each can do then it would get
really difficult to understand the differences.
A DOS program must be built using a 16-bit compiler and a 16-bit linker.
Microsoft Visual C++ (VC) version 1.52c is the latest version of VC that is
16-bit. For 32-bit programs a console program is specified using the Subsystem
option of the Linker Options. The Subsystem option has many subsystems types
that can be specified but only "CONSOLE" and "WINDOWS" are commonly used. When
the "CONSOLE" environment is specified a console application is created and when
the "WINDOWS" environment is specified a Windows GUI application is created. See
/SUBSYSTEM (Specify Subsystem) for an online copy of the Linker Subsystem
option in the MSDN. The
GetBinaryType function can be used to determine what Subsystem was specified for an
executable. I have a sample console program that uses the
GetBinaryType function in Getting Executable Type.
If you wish to use Standard I/O in a GUI program then you must first attach a
console. I think that is a function documented with the other console functions.
Next, look at Microsoft Knowledge Base (KB) Article "Calling CRT Output Routines
from a GUI Application" (Q105305).