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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 object-oriented languages ...
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 mathematical terms, an associative array is a function with finite domain. [1] It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. [2] The two major solutions to the dictionary problem are hash tables and search trees.
As in Perl 5, Perl 6 default hashes are flat: keys are strings and values are scalars. One can define a hash to not coerce all keys to strings automatically: these are referred to as "object hashes", because the keys of such hashes remain the original object rather than a stringification thereof.
Undefined parameter values are tricky: if the first positional parameter was not defined in the template call, then {{{1}}} will evaluate to the literal string "{{{1}}}" (i.e., the 7-character string containing three sets of curly braces around the number 1), which is a true value.
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 ...
In some programming languages, an assignment statement returns a value, while in others it does not. In most expression-oriented programming languages (for example, C), the assignment statement returns the assigned value, allowing such idioms as x = y = a, in which the assignment statement y = a returns the value of a, which is then assigned to x.
Python does not contain the classical for loop, rather a foreach loop is used to iterate over the output of the built-in range() function which returns an iterable sequence of integers. for i in range ( 1 , 6 ): # gives i values from 1 to 5 inclusive (but not 6) # statements print ( i ) # if we want 6 we must do the following for i in range ( 1 ...