Input Not On Command Prompt Dev C++

1. I am facing a problem in C,I want to execute a command in Command prompt from a specific path.I am able o select a path and execute cmd.exe using the function ShellExecute but the problem is after selecting the path I am not able to execute the command, the command is appearing on another command prompt.
2. Summary of basic C-commands Compiling To compile a C-program, you can use either gor c. Each command in C is followed by “;”. Carriage return has no meaning in C. Comments Essential for the writing of clear programs are comments, which are explana. Input And Output Input/Output With Screen.
3. Input parameters, i.e. Only passed to the function and are not changed within the function. The variables with “&” may be passed both to and from the function and may be changed in the function. Step 2: In the program you use the function with: function name (actual parameter list); example 1: feetinchtometer(5.0,3.2).
4. Well i use Dev-c 4.9.9.2 for programming.i m using it from last two years.recently i learned java and saw that all java programs are run through command prompt. I tried tha same in c. I saved my program in dev-cpp/bin.but i am not able to do this.what is the exact procedure please tell me. And How to pass command line argument.

• C++ Basics

Aug 05, 2015 I tried to upgrade to Windows 10 and as soon as it tries to boot up I get a floating box all over the screen that says 'Input not supported.' Command prompt. Command Line Argument in C. If any input value is passed through command prompt at the time of running of program is known as command line argument.It is a concept to passing the arguments to the main function by using command prompt. Putting C:Dev-Cppbin and C:Dev-Cpp on your PATH. The following assumes that you are logged on with Administrator privileges. Since that is the (amazingly insecure) default with Microsoft, you may assume that this is the case if you do not know otherwise.

• C++ Object Oriented

Command Prompt Codes

• C++ Advanced

• C++ Useful Resources

• Selected Reading

When we consider a C++ program, it can be defined as a collection of objects that communicate via invoking each other's methods. Let us now briefly look into what a class, object, methods, and instant variables mean.

• Object − Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behaviors - wagging, barking, eating. An object is an instance of a class.

• Class − A class can be defined as a template/blueprint that describes the behaviors/states that object of its type support.

• Methods − A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed.

• Instance Variables − Each object has its unique set of instance variables. An object's state is created by the values assigned to these instance variables.

C++ Program Structure

Let us look at a simple code that would print the words Hello World.

Let us look at the various parts of the above program −

• The C++ language defines several headers, which contain information that is either necessary or useful to your program. For this program, the header <iostream> is needed.

• The line using namespace std; tells the compiler to use the std namespace. Namespaces are a relatively recent addition to C++.

• The next line '// main() is where program execution begins.' is a single-line comment available in C++. Single-line comments begin with // and stop at the end of the line.

• The line int main() is the main function where program execution begins.

• The next line cout << 'Hello World'; causes the message 'Hello World' to be displayed on the screen.

• The next line return 0; terminates main( )function and causes it to return the value 0 to the calling process.

Compile and Execute C++ Program

Let's look at how to save the file, compile and run the program. Please follow the steps given below −

• Open a text editor and add the code as above.

• Save the file as: hello.cpp

• Open a command prompt and go to the directory where you saved the file.

• Type 'g++ hello.cpp' and press enter to compile your code. If there are no errors in your code the command prompt will take you to the next line and would generate a.out executable file.

• Now, type 'a.out' to run your program.

• You will be able to see ' Hello World ' printed on the window.

Make sure that g++ is in your path and that you are running it in the directory containing file hello.cpp.

You can compile C/C++ programs using makefile. For more details, you can check our 'Makefile Tutorial'.

Semicolons and Blocks in C++

In C++, the semicolon is a statement terminator. That is, each individual statement must be ended with a semicolon. It indicates the end of one logical entity.

For example, following are three different statements −

A block is a set of logically connected statements that are surrounded by opening and closing braces. For example −

C++ does not recognize the end of the line as a terminator. For this reason, it does not matter where you put a statement in a line. For example −

is the same as

C++ Identifiers

A C++ identifier is a name used to identify a variable, function, class, module, or any other user-defined item. An identifier starts with a letter A to Z or a to z or an underscore (_) followed by zero or more letters, underscores, and digits (0 to 9).

C++ does not allow punctuation characters such as @, $, and % within identifiers. C++ is a case-sensitive programming language. Thus, Manpower and manpower are two different identifiers in C++.

Here are some examples of acceptable identifiers −

C++ Keywords

The following list shows the reserved words in C++. These reserved words may not be used as constant or variable or any other identifier names.

asm	else	new	this
auto	enum	operator	throw
bool	explicit	private	true
break	export	protected	try
case	extern	public	typedef
catch	false	register	typeid
char	float	reinterpret_cast	typename
class	for	return	union
const	friend	short	unsigned
const_cast	goto	signed	using
continue	if	sizeof	virtual
default	inline	static	void
delete	int	static_cast	volatile
do	long	struct	wchar_t
double	mutable	switch	while
dynamic_cast	namespace	template

Trigraphs

A few characters have an alternative representation, called a trigraph sequence. A trigraph is a three-character sequence that represents a single character and the sequence always starts with two question marks.

Trigraphs are expanded anywhere they appear, including within string literals and character literals, in comments, and in preprocessor directives.

Following are most frequently used trigraph sequences −

Trigraph	Replacement
??=	#
??/
??'	^
??(	[
??)	]
??!	|
??<	{
??>	}
??-	~

All the compilers do not support trigraphs and they are not advised to be used because of their confusing nature.

Whitespace in C++

A line containing only whitespace, possibly with a comment, is known as a blank line, and C++ compiler totally ignores it.

Whitespace is the term used in C++ to describe blanks, tabs, newline characters and comments. Whitespace separates one part of a statement from another and enables the compiler to identify where one element in a statement, such as int, ends and the next element begins.

Statement 1

In the above statement there must be at least one whitespace character (usually a space) between int and age for the compiler to be able to distinguish them.

Statement 2

In the above statement 2, no whitespace characters are necessary between fruit and =, or between = and apples, although you are free to include some if you wish for readability purpose.

The example programs of the previous sections provided little interaction with the user, if any at all. They simply printed simple values on screen, but the standard library provides many additional ways to interact with the user via its input/output features. This section will present a short introduction to some of the most useful.
C++ uses a convenient abstraction called streams to perform input and output operations in sequential media such as the screen, the keyboard or a file. A stream is an entity where a program can either insert or extract characters to/from. There is no need to know details about the media associated to the stream or any of its internal specifications. All we need to know is that streams are a source/destination of characters, and that these characters are provided/accepted sequentially (i.e., one after another).
The standard library defines a handful of stream objects that can be used to access what are considered the standard sources and destinations of characters by the environment where the program runs:

stream	description
cin	standard input stream
cout	standard output stream
cerr	standard error (output) stream
clog	standard logging (output) stream

We are going to see in more detail only cout and

Visual C++ Command Prompt

cin (the standard output and input streams); cerr and clog are also output streams, so they essentially work like cout, with the only difference being that they identify streams for specific purposes: error messages and logging; which, in many cases, in most environment setups, they actually do the exact same thing: they print on screen, although they can also be individually redirected.

Standard output (cout)

On most program environments, the standard output by default is the screen, and the C++ stream object defined to access it is cout.
For formatted output operations, cout is used together with the insertion operator, which is written as << (i.e., two 'less than' signs).
The << operator inserts the data that follows it into the stream that precedes it. In the examples above, it inserted the literal string Output sentence, the number 120, and the value of variable x into the standard output stream cout. Notice that the sentence in the first statement is enclosed in double quotes (') because it is a string literal, while in the last one, x is not. The double quoting is what makes the difference; when the text is enclosed between them, the text is printed literally; when they are not, the text is interpreted as the identifier of a variable, and its value is printed instead. For example, these two sentences have very different results:

Multiple insertion operations (<<) may be chained in a single statement:
This last statement would print the text This is a single C++ statement. Chaining insertions is especially useful to mix literals and variables in a single statement:

Assuming the age variable contains the value 24 and the zipcode variable contains 90064, the output of the previous statement would be:
I am 24 years old and my zipcode is 90064
What cout does not do automatically is add line breaks at the end, unless instructed to do so. For example, take the following two statements inserting into cout:
cout << 'This is a sentence.';
cout << 'This is another sentence.';
The output would be in a single line, without any line breaks in between. Something like:
This is a sentence.This is another sentence.
To insert a line break, a new-line character shall be inserted at the exact position the line should be broken. In C++, a new-line character can be specified as n (i.e., a backslash character followed by a lowercase n). For example:
This produces the following output:
First sentence.
Second sentence.
Third sentence.

Alternatively, the endl manipulator can also be used to break lines. For example:

This would print:
First sentence.
Second sentence.

The endl manipulator produces a newline character, exactly as the insertion of 'n' does; but it also has an additional behavior: the stream's buffer (if any) is flushed, which means that the output is requested to be physically written to the device, if it wasn't already. This affects mainly fully buffered streams, and cout is (generally) not a fully buffered stream. Still, it is generally a good idea to use endl only when flushing the stream would be a feature and 'n' when it would not. Bear in mind that a flushing operation incurs a certain overhead, and on some devices it may produce a delay.

Standard input (cin)

In most program environments, the standard input by default is the keyboard, and the C++ stream object defined to access it is cin.
For formatted input operations, cin is used together with the extraction operator, which is written as >> (i.e., two 'greater than' signs). This operator is then followed by the variable where the extracted data is stored. For example:
The first statement declares a variable of type int called age, and the second extracts from cin a value to be stored in it. This operation makes the program wait for input from cin; generally, this means that the program will wait for the user to enter some sequence with the keyboard. In this case, note that the characters introduced using the keyboard are only transmitted to the program when the ENTER (or RETURN) key is pressed. Once the statement with the extraction operation on cin is reached, the program will wait for as long as needed until some input is introduced.
The extraction operation on cin uses the type of the variable after the >> operator to determine how it interprets the characters read from the input; if it is an integer, the format expected is a series of digits, if a string a sequence of characters, etc.

As you can see, extracting from cin seems to make the task of getting input from the standard input pretty simple and straightforward. But this method also has a big drawback. What happens in the example above if the user enters something else that cannot be interpreted as an integer? Well, in this case, the extraction operation fails. And this, by default, lets the program continue without setting a value for variable i, producing undetermined results if the value of i is used later.
This is very poor program behavior. Most programs are expected to behave in an expected manner no matter what the user types, handling invalid values appropriately. Only very simple programs should rely on values extracted directly from cin without further checking. A little later we will see how stringstreams can be used to have better control over user input.
Extractions on cin can also be chained to request more than one datum in a single statement:
This is equivalent to:

In both cases, the user is expected to introduce two values, one for variable a, and another for variable b. Any kind of space is used to separate two consecutive input operations; this may either be a space, a tab, or a new-line character.

cin and strings

The extraction operator can be used on cin to get strings of characters in the same way as with fundamental data types:
However, cin extraction always considers spaces (whitespaces, tabs, new-line...) as terminating the value being extracted, and thus extracting a string means to always extract a single word, not a phrase or an entire sentence.
To get an entire line from cin, there exists a function, called getline, that takes the stream (cin) as first argument, and the string variable as second. For example:

Notice how in both calls to getline, we used the same string identifier (mystr). What the program does in the second call is simply replace the previous content with the new one that is introduced.
The standard behavior that most users expect from a console program is that each time the program queries the user for input, the user introduces the field, and then presses ENTER (or RETURN). That is to say, input is generally expected to happen in terms of lines on console programs, and this can be achieved by using getline to obtain input from the user. Therefore, unless you have a strong reason not to, you should always use getline to get input in your console programs instead of extracting from cin.

stringstream

The standard header '><sstream> defines a type called stringstream that allows a string to be treated as a stream, and thus allowing extraction or insertion operations from/to strings in the same way as they are performed on cin and cout. This feature is most useful to convert strings to numerical values and vice versa. For example, in order to extract an integer from a string we can write:
This declares a string with initialized to a value of '1204', and a variable of type int. Then, the third line uses this variable to extract from a stringstream constructed from the string. This piece of code stores the numerical value 1204 in the variable called myint.

In this example, we acquire numeric values from the standard input indirectly: Instead of extracting numeric values directly from cin, we get lines from it into a string object (mystr), and then we extract the values from this string into the variables price and quantity. Once these are numerical values, arithmetic operations can be performed on them, such as multiplying them to obtain a total price.
With this approach of getting entire lines and extracting their contents, we separate the process of getting user input from its interpretation as data, allowing the input process to be what the user expects, and at the same time gaining more control over the transformation of its content into useful data by the program.

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Index

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