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The empty string has several properties: |ε| = 0. Its string length is zero. ε ⋅ s = s ⋅ ε = s. The empty string is the identity element of the concatenation operation. The set of all strings forms a free monoid with respect to ⋅ and ε. ε R = ε. Reversal of the empty string produces the empty string, so the empty string is a palindrome.
string.length() C++ (STL) string.length: Cobra, D, JavaScript: string.length() Number of UTF-16 code units: Java (string-length string) Scheme (length string) Common Lisp, ISLISP (count string) Clojure: String.length string: OCaml: size string: Standard ML: length string: Number of Unicode code points Haskell: string.length: Number of UTF-16 ...
In most encodings, this is translated to a single code unit with a zero value. For instance, in UTF-8 it is a single zero byte. However, in Modified UTF-8 the null character is encoded as two bytes: 0xC0,0x80. This allows the byte with the value of zero, which is now not used for any character, to be used as a string terminator.
The length of a string is the number of code units before the zero code unit. [1] The memory occupied by a string is always one more code unit than the length, as space is needed to store the zero terminator. Generally, the term string means a string where the code unit is of type char, which is exactly 8 bits on all modern machines.
The std::string class is the standard representation for a text string since C++98. The class provides some typical string operations like comparison, concatenation, find and replace, and a function for obtaining substrings. An std::string can be constructed from a C-style string, and a C-style string can also be obtained from one. [7]
This allows the string to contain NUL and made finding the length need only one memory access (O(1) (constant) time), but limited string length to 255 characters. C designer Dennis Ritchie chose to follow the convention of null-termination to avoid the limitation on the length of a string and because maintaining the count seemed, in his ...
The STL was created as the first library of generic algorithms and data structures for C++, with four ideas in mind: generic programming, abstractness without loss of efficiency, the Von Neumann computation model, [2] and value semantics. The STL and the C++ Standard Library are two distinct entities. [3]
C++11 provides solutions to all of these problems. C++11 allows constructors to call other peer constructors (termed delegation). This allows constructors to utilize another constructor's behavior with a minimum of added code. Delegation has been used in other languages e.g., Java and Objective-C. This syntax is as follows: