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String functions are used in computer programming languages to manipulate a string or query information about a string (some do both).. Most programming languages that have a string datatype will have some string functions although there may be other low-level ways within each language to handle strings directly.
In C++, the C++20 revision adds the spaceship operator <=>, which returns a value that encodes whether the 2 values are equal, less, greater, or unordered and can return different types depending on the strictness of the comparison. [3] The name's origin is due to it reminding Randal L. Schwartz of the spaceship in an HP BASIC Star Trek game. [4]
find the value (if any) that is bound to a given key. The argument to this operation is the key, and the value is returned from the operation. If no value is found, some lookup functions raise an exception, while others return a default value (such as zero, null, or a specific value passed to the constructor).
For example, one could define a dictionary having a string "toast" mapped to the integer 42 or vice versa. The keys in a dictionary must be of an immutable Python type, such as an integer or a string, because under the hood they are implemented via a hash function. This makes for much faster lookup times, but requires keys not change.
In Python, == compares by value. Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c. Python uses and, or, and not as Boolean operators. Python has a type of expression named a list comprehension, and a more general expression named a generator ...
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type.In statically typed languages, a nullable type is an option type, [citation needed] while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null ...
Despite the name, this is semantically similar to an implicit unit type, not a zero or bottom type (which is sometimes confusingly called the "void type"). Unlike a real unit type which is a singleton, the void type lacks a way to represent its value and the language does not provide any way to declare an object or represent a value with type void.
For example, two string objects may be distinct objects (unequal in the first sense) but contain the same sequence of characters (equal in the second sense). See identity for more of this issue. Real numbers, including many simple fractions , cannot be represented exactly in floating-point arithmetic , and it may be necessary to test for ...