Lecture 11: Compound/Composite Data Types

What are the most common compound data types

[1] arrays; [2] strings; [3] records; [4] structs; and [5] variant records.

what are arrays

Arrays are the most common compound/composite type found in programming languages.

What are the attributes of arrays

[1] the type of its elements. This is also the type of the composite type. [2] the type of its indices. Integers are normally used, but other type is possible, e.g., enumerated type. [3] the number of elements (or index range).

Describe static arrays

[1] Static arrays: subscript ranges (i.e., sizes of arrays) are statically bound and storage allocation is static (at compile time) [2]e.g., Pascal arrays, C/C++ arrays that include static modifier [3] Advantage: efficiency (no dynamic allocation)

describe Stack-dynamic arrays

[1] subscript ranges R dynamically bound, the storage allocation is at run-time. Lives on stack. size is fixed [2]E.g. C/C++ arrays w/out static modifier: double balance[10] [3] Advantage: flexibility (array size need not be known til the array is used)

describe Heap-dynamic arrays

[1] lives on heap and can change size. [2] C++ (via pointer), JavaScript, Python, etc. support these [3]E.g. in C++ myType *heapArray = new myType[100]; delete [] heapArray; [4] Advantage: flexibility (arrays can grow or shrink during program execution)

what are Heterogeneous Arrays

[1] A heterogeneous array is one in which the elements need NOT be of the same type. [2] Supported by Perl, Python, JavaScript.

What is a Jagged Array

A jagged array has rows with varying number of elements (but has no concept of columns). Therefore a jagged multiple-dimensional arrays are actually arrays of arrays.

What is a rectangular array

A rectangular array is a multi-dimensioned (e.g., 2D) array in which all of the rows have the same number of elements and all columns have the same number of elements

What are Records?

A record is composed of a number of named elements of data.

describe Structs versus Classes

Structurally, structs are similar to classes (without constructors), and “member function” is an alternative term for “method”.