Page 272 - DCAP404 _Object Oriented Programming

Unit 12: Console I/O

n = 14 Notes
p = 175
2. The setw manipulator does the job as follows:
cout <<setw(5) <<sum <<endl;

The manipulator setw(5) specifies a field width 5 for printing. The value of the variable
sum is printed as 5 digits. This value is right justified within the field.

3 4 5

We can also write our own manipulators as:
#include <iostream.h>

ostream & Symbol (ostream & output)
{
return output <<“\+`”;
}
The symbol is the new manipulator, which represents ` The identifier symbol can be used

Wherever we need to display the string “`”.
12.4.1 Manipulate Function

Manipulators are special functions that can be included in the I/O statements to alter the format
parameters of a stream. The most commonly used manipulators functions are given below. To
access these function, we must include the file iomanip.h in the program.
1. Setw (int w): As discussed earlier, this manipulator function is used to changes or set the
field width for output to w.

2. Set fill (char C): It is used to change or set the fill character to n (default is a space).
3. Set precision (int p): It is used to change or set the floating point precision to p.
4. Set base (base n): It is used to changes base to n, where n is 8, 10, or 16. If n is zero, output
is base 10, but input uses the C convention: 10 is 10, 010 is 8 and O x c is 12.
5. Set Pos flags (print flags f): This manipulator function changes or sets the format flag f.
Setting remain in effect until next change.

6. Reset i os flags (fmt flags f): This manipulators clears only the flags specified by f. Setting
remains in effect until next change.

12.4.2 Predefined Manipulators

Manipulators comes in tow flavors: Those take an argument as discussed in previous topic and
those that don’t. Manipulators with no arguments are known as predefined manipulators. These
are provided in iostream.h. The most commonly used predefined manipulators are given below:

1. end l; This manipulator sends a newline to the stream and flushes it.
2. skipws: It is used to skip white space on input.

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