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The Hexadecimal notation for null is 00. Decoding the Base64 string AA== also yields the null character. In documentation, the null character is sometimes represented as a single-em-width symbol containing the letters "NUL". In Unicode, there is a character for this: U+2400 ␀ SYMBOL FOR NULL.
The sequence \Uhhhhhhhh denotes the code point hhhhhhhh, interpreted as a hexadecimal number. Code points located at U+10000 or higher must be denoted with the \U syntax, whereas lower code points may use \u or \U. The code point is converted into a sequence of code units in the encoding of the
C designer Dennis Ritchie chose to follow the convention of null-termination to avoid the limitation on the length of a string and because maintaining the count seemed, in his experience, less convenient than using a terminator. [2] [3] This had some influence on CPU instruction set design.
The NULL character (code 0) is represented by Ctrl-@, "@" being the code immediately before "A" in the ASCII character set. For convenience, some terminals accept Ctrl-Space as an alias for Ctrl-@. In either case, this produces one of the 32 ASCII control codes between 0 and 31.
In C and C++, 0 represents the null pointer. As with Boolean values, the C standard library includes a macro definition NULL whose use is encouraged. Other languages provide a specific null or nil value and when this is the case no alternative should be used. The typed pointer constant nullptr has been introduced with C++11.
Most C compilers generate no code for null statements, which has historical and performance reasons. ; An empty block (compound statement) is also a NOP, and may be more legible, but will still have no code generated for it by the compiler. {} In some cases, such as the body of a function, a block must be used, but this can be empty.
unsigned int as a hexadecimal number. x uses lower-case letters and X uses upper-case. o: unsigned int in octal. s: null-terminated string. c: char (character). p: void* (pointer to void) in an implementation-defined format. a, A: double in hexadecimal notation, starting with 0x or 0X. a uses lower-case letters, A uses upper-case letters.
A snippet of C code which prints "Hello, World!". The syntax of the C programming language is the set of rules governing writing of software in C. It is designed to allow for programs that are extremely terse, have a close relationship with the resulting object code, and yet provide relatively high-level data abstraction.