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(However, default initialization to 0 is a right practice for pointers and arrays of pointers, since it makes them invalid before they are actually initialized to their correct value.) In C, variables with static storage duration that are not initialized explicitly are initialized to zero (or null, for pointers).
C++ enforces stricter typing rules (no implicit violations of the static type system [1]), and initialization requirements (compile-time enforcement that in-scope variables do not have initialization subverted) [7] than C, and so some valid C code is invalid in C++. A rationale for these is provided in Annex C.1 of the ISO C++ standard.
[5] new and delete were, in fact, introduced in the first version of C++ (then called "C with Classes") to avoid the necessity of manual object initialization. [4] In contrast to the C routines, which allow growing or shrinking an allocated array with realloc, it is not possible to change the size of a memory buffer allocated by new[].
In computer programming, initialization or initialisation is the assignment of an initial value for a data object or variable. The manner in which initialization is performed depends on the programming language , as well as the type, storage class, etc., of an object to be initialized.
As such, the compiler must also generate "hidden" code in the constructors of each class to initialize a new object's virtual table pointer to the address of its class's virtual method table. Many compilers place the virtual table pointer as the last member of the object; other compilers place it as the first; portable source code works either ...
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 table (CT2) is used to extract the index (from 2nd column) to the pointer array (CT2P). If pointer arrays are not supported, a SWITCH statement or equivalent can be used to alter the control flow to one of a sequence of program labels (e.g.: case0, case1, case2, case3, case4) which then either process the input directly, or else perform a ...
In computer programming, lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed. It is a kind of lazy evaluation that refers specifically to the instantiation of objects or other resources.