Chapter 4 INPUT AND OUTPUT OBJECTS
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Transcript of Chapter 4 INPUT AND OUTPUT OBJECTS
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;
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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
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• 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
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• Setting the Field Width
cout << setw(field width) << output item;
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• Generating Decimal Point Values
cout.setf(ios::fixed );cout.precision(n);
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• Generating Left-Justified Values
cout.setf(ios::fixed); cout.setf( ios::left);
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• Generating Currency Values
cout.setf(ios::fixed);cout.setf(ios::showpoint);cout.precision(2);
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• 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.
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• The cin ObjectThe cin object is used to read information from the keyboard and is contained in the iostream.h and iostream header files.
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CRLF889274
Keyboard
Input Stream
blank character
74 92 88 cin
• The cin Input Stream Flows from the Keyboard
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• 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.
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• Using get() and put() For Single Character Data
cin.get(character variable);cout.put(character variable);
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• 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.
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• 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