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Undefined
Undefined may refer to: Mathematics * Undefined (mathematics), with several related meanings ** Indeterminate form, in calculus Computing * Undefined behavior, computer code whose behavior is not specified under certain conditions * Undefined value, a condition where an expression does not have a correct value * Undefined variable * Undefined, a function or variable lacking a declaration (computer programming), declaration * Undefined, a variable lacking initialization (programming), initialization * Undefined, an unavailable dynamic linker, linker symbol (function, or global variable) Other uses * Undefined, something that lacks definition * Undefined citizenship, a post-Soviet form of statelessness in Estonia See also * Null (other) * Void (other) * Invalid (other) * Definition (other) * Definable (other) * {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undefined Behavior
In computer programming, undefined behavior (UB) is the result of executing a program whose behavior is prescribed to be unpredictable, in the language specification to which the computer code adheres. This is different from unspecified behavior, for which the language specification does not prescribe a result, and implementation-defined behavior that defers to the documentation of another component of the platform (such as the ABI or the translator documentation). In the C community, undefined behavior may be humorously referred to as "nasal demons", after a comp.std.c post that explained undefined behavior as allowing the compiler to do anything it chooses, even "to make demons fly out of your nose". Overview Some programming languages allow a program to operate differently or even have a different control flow than the source code, as long as it exhibits the same user-visible side effects, ''if undefined behavior never happens during program execution''. Undefined behavior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |