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In C, the functions strcmp and memcmp perform a three-way comparison between strings and memory buffers, respectively. They return a negative number when the first argument is lexicographically smaller than the second, zero when the arguments are equal, and a positive number otherwise.
Tests if two strings are equal. See also #Compare and #Compare. Note that doing equality checks via a generic Compare with integer result is not only confusing for the programmer but is often a significantly more expensive operation; this is especially true when using "C-strings".
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 ...
COBOL uses the STRING statement to concatenate string variables. MATLAB and Octave use the syntax "[x y]" to concatenate x and y. Visual Basic and Visual Basic .NET can also use the "+" sign but at the risk of ambiguity if a string representing a number and a number are together. Microsoft Excel allows both "&" and the function "=CONCATENATE(X,Y)".
Python 3.8 introduced assignment expressions, but uses the walrus operator := instead of a regular equal sign (=) to avoid bugs which simply confuse == with =. [ 13 ] Another disadvantage appears in C++ when comparing non-basic types as the == is an operator and there may not be a suitable overloaded operator function defined.
The distinct values are stored in a string intern pool. The single copy of each string is called its intern and is typically looked up by a method of the string class, for example String.intern() [2] in Java. All compile-time constant strings in Java are automatically interned using this method. [3]
It is at least the absolute value of the difference of the sizes of the two strings. It is at most the length of the longer string. It is zero if and only if the strings are equal. If the strings have the same size, the Hamming distance is an upper bound on the Levenshtein distance. The Hamming distance is the number of positions at which the ...
The standard example here is the languages L k consisting of all strings over the alphabet {a,b} whose kth-from-last letter equals a. On the one hand, a regular expression describing L 4 is given by ( a ∣ b ) ∗ a ( a ∣ b ) ( a ∣ b ) ( a ∣ b ) {\displaystyle (a\mid b)^{*}a(a\mid b)(a\mid b)(a\mid b)} .