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Author: Admin | 2025-04-28
When assigning a binary value and a hexadecimal value directly you can do it as follows (respectively):uint8_t val1 = 0b10101;uint8_t val2 = 0xFF;What does the 0b and 0x mean? Specifically the 0 at the front. Can you have other values instead of 0?Also as another curious question, what other characters can go in the place of b and x? Is there one for octal as an example? Neuron5,8515 gold badges43 silver badges62 bronze badges asked Aug 22, 2019 at 8:34 5 Any and all integer literals you can create are summarized in the C++ standard by the grammar production at [lex.icon]integer-literal: binary-literal integer-suffixopt octal-literal integer-suffixopt decimal-literal integer-suffixopt hexadecimal-literal integer-suffixoptbinary-literal: 0b binary-digit 0B binary-digit binary-literal 'opt binary-digitoctal-literal: 0 octal-literal 'opt octal-digitdecimal-literal: nonzero-digit decimal-literal 'opt digithexadecimal-literal: hexadecimal-prefix hexadecimal-digit-sequencebinary-digit: 0 1octal-digit: one of 0 1 2 3 4 5 6 7nonzero-digit: one of 1 2 3 4 5 6 7 8 9hexadecimal-prefix: one of 0x 0Xhexadecimal-digit-sequence: hexadecimal-digit hexadecimal-digit-sequence 'opt hexadecimal-digithexadecimal-digit: one of 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E FAs we can deduce from the grammar, there are four types of integer literals:Plain decimal, that must begin with a non-zero digit.Octal, any number with a leading 0 (including a plain 0).Binary, requiring the prefix 0b or 0B.Hexadecimal, requiring the prefix 0x or 0X.The leading 0 for octal numbers can be thought of as the "O" in "Octal". The other prefixes use a leading zero to mark the beginning of a number that should not be interpreted as decimal. "B" is intuitively for "binary", while "X" is for "hexadecimal". answered Aug 22, 2019 at 8:50 4 0b (or 0B) denotes a binary literal. C++ has allowed it since C++14. (It's not part of the C standard yet although some compilers allow it as an extension.) 0x (or 0X) is for hexadecimal.0 can be used to denote an octal literal. (Interestingly 0 itself is an octal literal). Furthermore you use the escape sequence \ followed by digits to be read in octal: this applies only when defining const char[] literals using "" or char or multicharacter literals using ''. The '\0' notation that you often see to denote NUL when working with strings exploits that.In the absence of a user defined literal suffix, any numeric literal starting with a non-zero is in denary.There are rumblings in the C++ world to use
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