No, it is not allowed to exceed the allocated size of an array. However, few compilers check, so if the programmer fails to check, he or she can get in trouble, by corrupting other memory or throwing a bus exception.
(array.length - 1) will find the index of the last element in an array (or -1 if the array is empty).
Basically, &array[i]; That is, the memory location for an array object with index i. Or, you can do: (array + i);
Array subscripts always have a zero-based index. In languages that allow an n-based index, the index is simply offset by n elements, so the compiler subtracts n from the given index to obtain the zero-based index. Arrays are always zero-based because the first element of an array is found zero elements from the start of the array.
All languages use zero-based subscripting to index array elements because the first element is always allocated zero elements from the start address of the array. Very few languages default to a one-based subscript, however some languages, including VBScript, do allow you to change the lower-bound. Some algorithms are easier to implement with one-based subscripting, however you can also choose any lower and upper bound as appropriate.
// Pseudocode int findMax( int[][] data ) { // Return if data is empty if( data.length 0 ) { return 0; } int max = data[0][0]; // Iterate through each element in the array for( int r = 0; r < data.length; ++r ) { for( int c = 0; c < data[0].length; ++c ) { // If we find a value greater than the current max, update max if( data[r][c] > max ) { max = data[r][c]; } } } return max; }
Traverse the array from index 0 until you find the number. Return the index of that number.
By design; it makes the compiler's work easier. 1-based array's addressing-function: Address (array, index) = Address (array) + (index-1)*Elemsize(array) 0-based array's addressing-function: Address (array, index) = Address (array) + index*Elemsize (array)
The details depend on the language, but the index of an array is usually an integer data type. Anything that is compatible with an integer can be used.
(array.length - 1) will find the index of the last element in an array (or -1 if the array is empty).
A key is the name of a variable in an array ($array["key"]) and the index is the position it's at ($array = ["key" => 0], the index would be 0). Keys and indices are the same if the array is not associative though ($array = [true], the key holding the value true is named 0 and is at index 0).
Basically, &array[i]; That is, the memory location for an array object with index i. Or, you can do: (array + i);
Array subscripts always have a zero-based index. In languages that allow an n-based index, the index is simply offset by n elements, so the compiler subtracts n from the given index to obtain the zero-based index. Arrays are always zero-based because the first element of an array is found zero elements from the start of the array.
All languages use zero-based subscripting to index array elements because the first element is always allocated zero elements from the start address of the array. Very few languages default to a one-based subscript, however some languages, including VBScript, do allow you to change the lower-bound. Some algorithms are easier to implement with one-based subscripting, however you can also choose any lower and upper bound as appropriate.
For an array of length s, the last element has index s-1.
// Pseudocode int findMax( int[][] data ) { // Return if data is empty if( data.length 0 ) { return 0; } int max = data[0][0]; // Iterate through each element in the array for( int r = 0; r < data.length; ++r ) { for( int c = 0; c < data[0].length; ++c ) { // If we find a value greater than the current max, update max if( data[r][c] > max ) { max = data[r][c]; } } } return max; }
Since an array cannot contain a negative number of items, the size of an array must be at least 0. So if you ever tried to retrieve the element at a negative index in an array, it would automatically be understood to be out-of-bounds.
Because that's how the language is defined. In C, C++, and many other languages, array indecies start with zero. This is by convention, and it also reflects the fact that, in C and C++, array-index syntax can also be expressed in pointer-offset syntax. The pointer locates the first element of the array, and the offset indicates how many elements to skip. If a is an array name, then the expression a[n] is completely identical to the expression *(a+n), and vice versa.