Computer Science - Object Oriented Programming Using C++ - Discussion

cout and cin contain several single-bit flags for format control. They are named in an enum in class ios as:

ios::skipws // skips whitspace on input
ios::left // left justification
ios::right // right justifiction
ios::internal // pads after sign or base character
ios::dec // decimal format for integers
ios::oct // octal format for integers
ios::hex // hex format for integers
ios::showbase // show the base character for octal or hex
ios::showpoint // show the decimal point for all floats
ios::uppercase // uppercase A-F for hex
ios::showpos // show +ve sign for numbers
ios::scientific // use exponential notation
ios::fixed // used oridnary decimal notation
ios::unitbuf // flush the buffer

These flags can be set with the member function setf. e.g.

cout.setf(ios::showpos);

They can be or'd together:
cout.setf(ios::showpos | ios::uppercase);
or some bits can be unset while one is being set:
cout.setf(ios::oct, ios::dec | ios::oct | ios::hex);

This sets the bit for oct, after unsetting the bits for oct, dec and hex, ensuring that only one of the bits is turned on.
unsetf turns bits off:
cout.unsetf(ios::showpos);

The class ios contains data members to store all the formatting information pertaining to a stream. Some of this data has a range of values and is stored in variables: the floating-point precision, the output field width, and the character used to pad the output (normally a space). The rest of the formatting is determined by flags, which are usually combined to save space and are referred to collectively as the format flags.

Let me explain in clear.

// Assume two 16-bit flags contains values as given below
intFlag1 = (00000000 10101010) In Binary.
intFlag2 = (00000010 01010101) In Binary.

// Now combine it with Bitwise-OR operator
intResult = intFlag1 | intFlag2 ;

// The combined result will be.
intResult = (00000010 11111111) In Binary.

Hope this will help you. Have a nice day!

The <iostream> library defines a rich set of format flags. These flags enable you to control the width, alignment, precision, and so on for the displayed data.

Actually bitwise OR operator is denoted by pipe symbol (|) which is use to combine.

Can anyone tell me what is format flags, and what is its use?

What are format flags? Please describe it in detail.

It is actually very beneficial. Thanks @Sunder.

Can any one explain that what are format flags?

3what is mean by format flag? Explain, please.