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Rays emanating from 0 in the z-plane are mapped to horizontal lines in the w-plane. Each circle and ray in the z-plane as above meet at a right angle. Their images under Log are a vertical segment and a horizontal line (respectively) in the w-plane, and these too meet at a right angle. This is an illustration of the conformal property of Log.
Perl autovivification can be contrasted against languages such as Python, PHP, Ruby, and many of the C style languages, where dereferencing null or undefined values is not generally permitted. [ a ] It can be compared to the HTML standard's "named access on the window object" [ 2 ] which results in corresponding globally scoped variables being ...
The STL provides a set of common classes for C++, such as containers and associative arrays, that can be used with any built-in type or user-defined type that supports some elementary operations (such as copying and assignment). STL algorithms are independent of containers, which significantly reduces the complexity of the library.
An undefined variable in the source code of a computer program is a variable that is accessed in the code but has not been declared by that code. [1] In some programming languages, an implicit declaration is provided the first time such a variable is encountered at compile time. In other languages such a usage is considered to be sufficiently ...
In the C and C++ languages, such non-portable constructs are generally grouped into three categories: Implementation-defined, unspecified, and undefined behavior. [3] The exact definition of unspecified behavior varies. In C++, it is defined as "behavior, for a well-formed program construct and correct data, that depends on the implementation."
The memory model defined in the C11 and C++11 standards specify that a C or C++ program containing a data race has undefined behavior. [ 3 ] [ 4 ] A race condition can be difficult to reproduce and debug because the end result is nondeterministic and depends on the relative timing between interfering threads.
An undefined value must not be confused with empty string, Boolean "false" or other "empty" (but defined) values. Depending on circumstances, evaluation to an undefined value may lead to exception or undefined behaviour , but in some programming languages undefined values can occur during a normal, predictable course of program execution.
The C headers <stdnoreturn.h> and <threads.h> do not have C++ equivalents and their C headers are not supported in C++. C++ does not provide the C POSIX library as part of any standard, however it is legal to use in a C++ program. If used in C++, the POSIX headers are not prepended with a "c" at the beginning of the name, and all contain the .h ...