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In computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as an array index is within the bounds of the array (index checking).
When an array is numerically indexed, its range is the upper and lower bound of the array. Depending on the environment, a warning, a fatal exception , or unpredictable behavior will occur if the program attempts to access an array element that is outside the range.
Classes are reference types and structs are value types. A structure is allocated on the stack when it is declared and the variable is bound to its address. It directly contains the value. Classes are different because the memory is allocated as objects on the heap. Variables are rather managed pointers on the stack which point to the objects.
One common example is accessing an array element, modifying it, and storing the modified value in the same array at the same location. Normally, this example would result in a bounds check when the element is read from the array and a second bounds check when the modified element is stored using the same array index.
A reference variable, once declared and bound, behaves as an alias of the original variable, but it can also be rebounded to another variable by using the reference assignment operator = ref. The variable itself can be of any type, including value types and reference types, i.e. by passing a variable of a reference type by reference (alias) to ...
In Rust the ..= operator denotes an inclusive range for cases in matches and the .. operator represents a range not including the end value. Perl and Ruby overload the ".." operator in scalar context as a flip-flop operator - a stateful bistable Boolean test, roughly equivalent to "true while x but not yet y", similarly to the "," operator in ...
The primary facility for accessing the values of the elements of an array is the array subscript operator. To access the i-indexed element of array, the syntax would be array[i], which refers to the value stored in that array element. Array subscript numbering begins at 0 (see Zero-based indexing). The largest allowed array subscript is ...
All the operators (except typeof) listed exist in C++; the column "Included in C", states whether an operator is also present in C. Note that C does not support operator overloading. When not overloaded, for the operators && , || , and , (the comma operator ), there is a sequence point after the evaluation of the first operand.