G-I

garbage collection

If only implicit dynamic allocation is allowed then deallocation must also be done by implicit means, which is often called garbage collection.

garbage collector

Software that provides implicit memory deallocation by deallocating objects that are no longer referenced by some other object.

getenv()

A UNIX system call to obtain the value of a particular environment variable.

GetEnvironmentVariable

A Windows system call to obtain the value of a particular environment variable.

global item

An item that can be referenced (accessed) in all functions (with some restrictions) of the program.

Hanoi towers puzzle

The Hanoi towers puzzle was invented by the French mathematician Edouard Lucas in 1883. Three pegs are given, one of which contains a certain number of wooden disks of different sizes. The disks must always be organized so that only a smaller disk can sit on top of a bigger one. The monks are supposed to move the disks from one peg to another. This is a complex problem that nevertheless can easily be " solved " using recursion (see Appendix A).

hidden allocation

A problem that arises when a service or object is requested from a module without realizing that the module has allocated some memory to serve that request.

incorrect assignment

An assignment that does not properly destroy the dynamic parts of an object before assigning them new values; usually in the form of a missing explicit assignment.

index-out-of-range run-time error

An attempt to access an array item with an index that is outside of the range.

indirection operator *

An operator referencing the "virtual object" at the address a pointer is pointing to; used for fetching and storing of values.

information hiding

A principle akin to the military term "need to know basis" whereby only the module that " guards " the data should have direct access to it while all other modules should gain access only through the "guard"; this enables much safer programming, for it prevents accidental data corruption.

inheritance

A mechanism by which objects of a derived class automatically have the same properties as objects of the base class without those properties being explicitly restated.

inlining

A method by which a compiler, in order to reduce the function overhead, places a direct code instead of a function call while maintaining the syntax convention and convenience of function calls.

innate data type

A synonym for elementary data type.

instance

A synonym for object.

instantiation

A synonym for object construction.

insufficient destructor

A destructor that does not properly deallocate all the dynamic parts of an object; usually in the form of a missing explicit destructor.

interpreted program

A program that is read in its source form by an interpreter that then does whatever the statements of the program indicate should be done.

interpreter

A program that reads (interprets) programs in their source form and executes whatever the statements of the program being interpreted indicate should be done.

invocation(of a function)

A synonym for function call.

ipcrm

A UNIX command for removal of a shared memory segment or a semaphore (provided the user has the required permissions to do so).

ipcs

A UNIX command for generating statistics on all shared memory segments and semaphores within the system.