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Many instances of the most commonly used garbage-collected type, the string, have a short lifetime, since they are typically intermediate values in string manipulation. A lot of local string usage could be optimized away, but the compiler currently doesn't do it. The reference count of a string is checked before mutating a string.
The C99 Language Specification ( ISO9899:1999 ) has the following warning in section 6.3.2.3 Pointers : "A pointer to an object or incomplete type may be converted to a pointer to a different object or incomplete type. If the resulting pointer is not correctly aligned for the pointed-to type, the behavior is undefined."
A basic example is in the argv argument to the main function in C (and C++), which is given in the prototype as char **argv—this is because the variable argv itself is a pointer to an array of strings (an array of arrays), so *argv is a pointer to the 0th string (by convention the name of the program), and **argv is the 0th character of the ...
The length of a string can also be stored explicitly, for example by prefixing the string with the length as a byte value. This convention is used in many Pascal dialects; as a consequence, some people call such a string a Pascal string or P-string. Storing the string length as byte limits the maximum string length to 255.
For string keys, space can be saved by using the following technique: Normally the i-th entry of an internal block contains the first key of block + . Instead of storing the full key, we could store the shortest prefix of the first key of block i + 1 {\displaystyle i+1} that is strictly greater (in lexicographic order) than last ...
LCS distance is bounded above by the sum of lengths of a pair of strings. [1]: 37 LCS distance is an upper bound on Levenshtein distance. For strings of the same length, Hamming distance is an upper bound on Levenshtein distance. [1] Regardless of cost/weights, the following property holds of all edit distances:
Numeric literals in Python are of the normal sort, e.g. 0, -1, 3.4, 3.5e-8. Python has arbitrary-length integers and automatically increases their storage size as necessary. Prior to Python 3, there were two kinds of integral numbers: traditional fixed size integers and "long" integers of arbitrary size.
In computer science, a tagged pointer is a pointer (concretely a memory address) with additional data associated with it, such as an indirection bit or reference count.This additional data is often "folded" into the pointer, meaning stored inline in the data representing the address, taking advantage of certain properties of memory addressing.