CSC204 Chapter 6: Data Types

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Questions and Answers

What is the primary function of a data type?

To define the behavior of a program

To define a collection of data values and a set of predefined operations (correct)

To define the workflow of a program

To define the input and output of a program

What are primitive data types?

Data types that are complex and hard to implement

Data types that are merely reflections of the hardware (correct)

Data types that require significant non-hardware support

Data types defined in terms of other data types

What is the most common primitive numeric data type?

Double

Boolean

Integer (correct)

Float

How are negative integers typically stored in computers?

In twos complement notation Signup and view all the answers

What is the purpose of floating-point data types?

To model real numbers, but only as approximations Signup and view all the answers

What is the range of values for a Boolean data type?

Two elements, one for “true” and one for “false” Signup and view all the answers

What is the typical difference in storage size between float and double floating-point variables?

Double variables usually occupy twice as much storage as float variables Signup and view all the answers

What is an object in the context of data types?

An instance of a user-defined data type Signup and view all the answers

What is a characteristic of enumeration types?

They provide a set of named constants. Signup and view all the answers

What is an advantage of using enumeration types?

They aid readability by removing the need to code values as numbers. Signup and view all the answers

What is a characteristic of arrays?

Elements are identified by their relative position. Signup and view all the answers

What is the purpose of indexing (or subscripting) in arrays?

To map indices to elements. Signup and view all the answers

In which languages are parentheses used for indexing?

FORTRAN, PL/I, and Ada Signup and view all the answers

What is the purpose of enumeration variables?

To restrict values to a defined range. Signup and view all the answers

What is true about assignment to enumeration variables?

Assignment is restricted to defined values. Signup and view all the answers

What is a benefit of using arrays?

They facilitate homogeneous data storage. Signup and view all the answers

What is a characteristic of a rectangular array?

All rows have the same number of elements, and all columns have the same number of elements Signup and view all the answers

Which of the following languages support jagged arrays?

C, C++, and Java Signup and view all the answers

How is a single-dimensioned array implemented?

As a list of adjacent memory cells Signup and view all the answers

What is an associative array?

An unordered collection of data elements that are indexed by an equal number of values Signup and view all the answers

What is the fundamental difference between a record and an array?

The way elements are referenced Signup and view all the answers

What is a characteristic of array initialization in Java?

It can be done at the time of storage allocation Signup and view all the answers

What is a characteristic of an array in C and C++?

It can be initialized using character strings Signup and view all the answers

What is a characteristic of record types in C, C++, and C#?

They are heterogeneous aggregates of data elements Signup and view all the answers

What is the function of the asterisk (*) in C and C++?

Denotes the dereferencing operation Signup and view all the answers

What is a reference type in C++?

A pointer type that refers to an object or a value in memory Signup and view all the answers

What is the purpose of type checking in a programming language?

To ensure the operands of an operator are of compatible types Signup and view all the answers

What is coercion in a programming language?

Automatic conversion done by the compiler/interpreter Signup and view all the answers

Which of the following languages are not strongly typed?

C and C++ Signup and view all the answers

What is a type error in a programming language?

Application of an operator to an operand of an inappropriate type Signup and view all the answers

What is the effect of coercion rules on type checking in a language?

It has a significant effect on type checking Signup and view all the answers

What is the result of assigning a value to a reference type in C++?

The value is assigned to the variable being referred to Signup and view all the answers

What notation is commonly used for field references in most languages?

Dot notation Signup and view all the answers

When are arrays typically used in programming?

When data values are of the same type and processed in the same way Signup and view all the answers

What is a characteristic of access to record fields?

Access is much faster than access to array elements Signup and view all the answers

What is the purpose of a pointer type variable?

To provide a way to manage dynamic memory Signup and view all the answers

What are the two fundamental operations of pointers?

Assignment and dereferencing Signup and view all the answers

What is the purpose of dereferencing in pointer operations?

To yield the value stored at the location represented by the pointer's value Signup and view all the answers

What is a characteristic of pointers in C and C++?

They are extremely flexible but must be used with care Signup and view all the answers

What is a feature of pointer arithmetic in C and C++?

It is possible to perform arithmetic operations on pointers Signup and view all the answers

Study Notes

Data Types

A data type defines a collection of data values and a set of predefined operations on those values.
A descriptor is the collection of the attributes of a variable.
An object represents an instance of a user-defined (abstract data) type.

Primitive Data Types

Primitive data types are not defined in terms of other data types.
Examples of primitive data types include integers, floating-point numbers, and booleans.

Integer Data Type

Integer is a primitive numeric data type.
Java has four signed integer sizes: byte, short, int, and long.
Negative integers can be stored in sign-magnitude notation or two's complement notation.

Floating-Point Data Type

Floating-point values are represented as fractions and exponents, similar to scientific notation.
Most languages support at least two floating-point types: float and double.
Double variables usually occupy twice as much storage as float variables.

Boolean Data Type

Boolean is the simplest of all types, with only two values: true and false.

Enumeration Types

An enumeration type is a set of named constants.
Example: enum days {mon, tue, wed, thu, fri, sat, sun};
Enumeration types aid readability and reliability by preventing invalid values from being assigned.

Array Types

An array is a homogeneous aggregate of data elements, where each element is identified by its position in the aggregate.
The individual data elements of an array are of the same type.
References to individual array elements are specified using subscript expressions.

Array Initialization

Some languages allow initialization of arrays at the time of storage allocation.
Examples: int list [] = {4, 5, 7, 83}; and char name [] = “freddie”;

Rectangular and Jagged Arrays

A rectangular array is a multi-dimensional array where all rows have the same number of elements.
A jagged array has rows with varying numbers of elements.
C, C++, and Java support jagged arrays.

Associative Arrays

An associative array is an unordered collection of data elements indexed by an equal number of values called keys.
Example: %hi_temps = ("Mon" => 77, "Tue" => 79, "Wed" => 65, …);

Record Types

A record is a heterogeneous aggregate of data elements, where individual elements are identified by names.
Records are supported in C, C++, and C# using the struct data type.
The fundamental difference between a record and an array is that record elements are not referenced by indices.

Pointer and Reference Types

A pointer type variable has a range of values that consists of memory addresses and a special value, nil.
Pointers provide the power of indirect addressing and a way to manage dynamic memory.
Dereferencing yields the value stored at the location represented by the pointer’s value.

Type Checking and Strong Typing

Type checking is the activity of ensuring that the operands of an operator are of compatible types.
Strongly typed languages detect type errors at compile time or runtime.
Examples: C and C++ are not strongly typed languages, while Java and C# are nearly strongly typed.

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Description

This quiz covers the basics of data types, including primitive, character string, enumeration, array, associative arrays, record, and pointer types, as well as type checking.