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A null pointer has a value reserved for indicating that the pointer does not refer to a valid object. Null pointers are routinely used to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types and to the Nothing value in an option type.
On many common platforms, this use of pointer punning can create problems if different pointers are aligned in machine-specific ways. Furthermore, pointers of different sizes can alias accesses to the same memory, causing problems that are unchecked by the compiler. Even when data size and pointer representation match, however, compilers can ...
In the C++ programming language, input/output library refers to a family of class templates and supporting functions in the C++ Standard Library that implement stream-based input/output capabilities. [ 1 ] [ 2 ] It is an object-oriented alternative to C's FILE -based streams from the C standard library .
C supports the use of pointers, a type of reference that records the address or location of an object or function in memory. Pointers can be dereferenced to access data stored at the address pointed to, or to invoke a pointed-to function. Pointers can be manipulated using assignment or pointer arithmetic. The run-time representation of a ...
Many languages have explicit pointers or references. Reference types differ from these in that the entities they refer to are always accessed via references; for example, whereas in C++ it's possible to have either a std:: string and a std:: string *, where the former is a mutable string and the latter is an explicit pointer to a mutable string (unless it's a null pointer), in Java it is only ...
External code can only use an object by calling a specific instance method with a certain set of input parameters, reading an instance variable, or writing to an instance variable. A program may create many instances of objects as it runs, which operate independently.
C++ programmers expect the latter on every major implementation of C++; it includes aggregate types (vectors, lists, maps, sets, queues, stacks, arrays, tuples), algorithms (find, for_each, binary_search, random_shuffle, etc.), input/output facilities (iostream, for reading from and writing to the console and files), filesystem library ...
Standard input is a stream from which a program reads its input data. The program requests data transfers by use of the read operation. Not all programs require stream input. For example, the dir and ls programs (which display file names contained in a directory) may take command-line arguments, but perform their operations without any stream ...