Chapter 4INPUT AND OUTPUT OBJECTS

Chapter 4

• The cout ObjectThe cout object is used to display information to the monitor and is contained in the iostream.h and iostream header files.

Chapter 4

• Using the cout Object

cout << item #1 << item #2 << item #3 << ·· << item #n;

Chapter 4

Monitor

<< item #1 << item #2 << item #3 ... << item #n;

item #1 item #2 item #nitem #3 ...

Stream of Data Items to be Displayed

cout

cout

• The cout Output Stream Flows to the System Monitor

Chapter 4

HELLO-

Cursor returns to beginning of next line.

HELLO -

Cursor remains at next positionon current line.

cout << "HELLO";

cout << "HELLO\n";

cout << "HELLO" << endl;

OR

• Using \n and endl

Chapter 4

• The C++ Escape Sequences Used with cout

\a Beep

\b Backspace

\n CRLF

\r CR

\t Horizontal tab

\v Vertical tab

\\ Backslash

\' Single quote

\” Double quote

\? Question mark

Chapter 4

• I/O Stream Manipulatorssetw(n) Sets field width to nsetprecision(n) Sets floating-point

precision to nsetfill(n) Sets fill character to nws Extracts white space charactersendl Inserts a new line in the output

stream, thenflush Flushes the output stream

Chapter 4

• Setting the Field Width

cout << setw(field width) << output item;

Chapter 4

• Generating Decimal Point Values

cout.setf(ios::fixed );cout.precision(n);

Chapter 4

• Generating Left-Justified Values

cout.setf(ios::fixed); cout.setf( ios::left);

Chapter 4

• Generating Currency Values

cout.setf(ios::fixed);cout.setf(ios::showpoint);cout.precision(2);

Chapter 4

• Formatting Functions and Flags

setf() Sets a formatting flag. unsetf() Unsets a formatting flag.

precision(n) Sets decimal output to n decimal places.

fixed Forces fixed decimal point output.

left Forces left justification within field.

right Forces right justification within field.

scientific Forces exponential, e, output.

showpoint Forces a decimal point to be displayed along with trailing 0’s.(Used for currency outputs)

showpos Forces a + sign output for positive values.

Chapter 4

• The cin ObjectThe cin object is used to read information from the keyboard and is contained in the iostream.h and iostream header files.

Chapter 4

CRLF889274

Keyboard

Input Stream

blank character

74 92 88 cin

• The cin Input Stream Flows from the Keyboard

Chapter 4

• Using the cin Objectcin >> variable to be read;

– Only one character is read at a time.– White space (blanks, tabs, new lines, carriage

returns, etc.) are ignored by cin when using the >> operator. However, white space can be read using different cin functions.

– Numeric values can be read as characters, but each digit is read as a separate character.

Chapter 4

• Using get() and put() For Single Character Data

cin.get(character variable);cout.put(character variable);

Chapter 4

• Reading Strings Using getline()

getline(input stream, string object,

'delimiting character’);– To avoid a potential problem, use the line

cin >> ws before the cin.getline() statement.

Chapter 4

• Opening an Input Fileifstream fin(”file path");

• Opening an Output Fileofstream fout(”file path");

• Opening an Input/Output Filefstream finout(“file path”);

Chapter 4

• Processing an Open File if(!fileObject)

{

cout << "This file cannot be opened" << endl;

exit(1);

}//END IF

else

{

while (Read Data Item From Input File )

{ //BEGIN LOOP

Process data item.

} //END LOOP

}//END ELSE