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Flexible array members were officially standardized in C99. [4] In practice, compilers (e.g., GCC , [ 5 ] MSVC [ 6 ] ) provided them well before C99 was standardized. Flexible array members are not officially part of C++ , but language extensions [ 7 ] are widely available.
A problem with this approach is that more complicated expressions such as Vec x = a + b + c are implemented inefficiently. The implementation first produces a temporary Vec to hold a + b, then produces another Vec with the elements of c added in. Even with return value optimization this will allocate memory at least twice and require two loops.
Nested ternaries can be simulated as c (expr1, expr2, expr3)[which.first ((c (cond1, cond2, TRUE))] where the function which.first returns the index of the first true value in the condition vector. Note that both of these map equivalents are binary operators, revealing that the ternary operator is ternary in syntax, rather than semantics.
The most vexing parse is a counterintuitive form of syntactic ambiguity resolution in the C++ programming language. In certain situations, the C++ grammar cannot distinguish between the creation of an object parameter and specification of a function's type.
Initialization is distinct from (and preceded by) declaration, although the two can sometimes be conflated in practice. The complement of initialization is finalization, which is primarily used for objects, but not variables. Initialization is done either by statically embedding the value at compile time, or else by assignment at run time.
The lazy initialization technique allows us to do this in just O(m) operations, rather than spending O(m+n) operations to first initialize all array cells. The technique is simply to allocate a table V storing the pairs ( k i , v i ) in some arbitrary order, and to write for each i in the cell T [ k i ] the position in V where key k i is stored ...
The vector maintains a certain order of its elements, so that when a new element is inserted at the beginning or in the middle of the vector, subsequent elements are moved backwards in terms of their assignment operator or copy constructor. Consequently, references and iterators to elements after the insertion point become invalidated. [8]
Assume that an attacker has observed two messages C 1 and C 2 both encrypted with the same key and IV. Then knowledge of either P 1 or P 2 reveals the other plaintext since C 1 xor C 2 = (P 1 xor K) xor (P 2 xor K) = P 1 xor P 2. Many schemes require the IV to be unpredictable by an adversary. This is effected by selecting the IV at random or ...