13.7.4. Integral Stream Base (dec, oct, hex, showbase)
C++ provides stream manipulators dec, hex and oct to specify that integers are to be displayed as decimal, hexadecimal and octal values, respectively. Stream insertions default to decimal if none of these manipulators is used. With stream extraction, integers prefixed with
0 (zero) are treated as octal values, integers prefixed with
0X are treated as hexadecimal values, and all other integers are treated as decimal values. Once a particular base is specified for a stream, all integers on that stream are processed using that base until a different base is specified or until the program terminates.
Stream manipulator showbase forces the base of an integral value to be output. Decimal ...