Search results
Results from the WOW.Com Content Network
2.3 C++17. 3 See also. 4 References. ... = i++; (where a is an array and i is an integer) has undefined behavior ... ->*, and the subscript and function call operator ...
The same is syntactically valid but has undefined behavior in C++, [8] however, where only the last-written member of a union is considered to have any value at all. For another example of type punning, see Stride of an array.
In C and C++ arrays do not support the size function, so programmers often have to declare separate variable to hold the size, and pass it to procedures as a separate parameter. Elements of a newly created array may have undefined values (as in C), or may be defined to have a specific "default" value such as 0 or a null pointer (as in Java).
Indexes are also called subscripts. An index maps the array value to a stored object. There are three ways in which the elements of an array can be indexed: 0 (zero-based indexing) The first element of the array is indexed by subscript of 0. [8] 1 (one-based indexing) The first element of the array is indexed by subscript of 1. n (n-based indexing)
In these three, sequence types (C arrays, Java arrays and lists, and Lisp lists and vectors) are indexed beginning with the zero subscript. Particularly in C, where arrays are closely tied to pointer arithmetic, this makes for a simpler implementation: the subscript refers to an offset from the starting position of an array, so the first ...
Though logically the last subscript in an array of 10 elements would be 9, subscripts 10, 11, and so forth could accidentally be specified, with undefined results. Due to arrays and pointers being interchangeable, the addresses of each of the array elements can be expressed in equivalent pointer arithmetic. The following table illustrates both ...
For example, many programming languages provide special syntax for referencing and updating array elements. Abstractly, an array reference is a procedure of two arguments: an array and a subscript vector, which could be expressed as get_array(Array, vector(i,j)). Instead, many languages provide syntax such as Array[i,j].
This can be understood as taking a null pointer of type structure st, and then obtaining the address of member m within said structure. While this implementation works correctly in many compilers, it has generated some debate regarding whether this is undefined behavior according to the C standard, [2] since it appears to involve a dereference of a null pointer (although, according to the ...