Data Types and Arrays in Programming
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Questions and Answers

A data type defines a collection of data values and a set of predefined operations on those values.

True

Primitive data types are defined in terms of other data types.

False

Java includes five signed integer sizes.

False

Floating-point types can exactly represent all real numbers.

<p>False</p> Signup and view all the answers

The precision of a floating-point type is measured by the number of bits representing the entire value.

<p>False</p> Signup and view all the answers

C++ and C# include unsigned integer types for values without signs.

<p>True</p> Signup and view all the answers

Descriptors for static attributes are required only at runtime.

<p>False</p> Signup and view all the answers

Type checking is one of the functions performed by descriptors.

<p>True</p> Signup and view all the answers

The element type in an array is the same as the type of subscript.

<p>False</p> Signup and view all the answers

Static arrays have their subscript ranges dynamically bound.

<p>False</p> Signup and view all the answers

A heap-dynamic array allows subscript ranges to change during its lifetime.

<p>True</p> Signup and view all the answers

In C++, string constants are implemented as arrays of integers.

<p>False</p> Signup and view all the answers

A fixed stack-dynamic array has its storage allocated before runtime.

<p>False</p> Signup and view all the answers

Arrays in C# cannot be initialized at the time of storage allocation.

<p>False</p> Signup and view all the answers

The array 'name' declared as char name [] = 'Freddie'; contains 7 elements.

<p>False</p> Signup and view all the answers

Fixed heap-dynamic arrays allow the subscript ranges to be dynamically bound only after their storage is allocated.

<p>True</p> Signup and view all the answers

In Python, a complex number is represented in the form (3 + 7j).

<p>False</p> Signup and view all the answers

Decimal types have an advantage of a wide range due to their use of exponents.

<p>False</p> Signup and view all the answers

Boolean values can typically be represented in memory as a single bit.

<p>True</p> Signup and view all the answers

ASCII is an 8-bit coding system that was traditionally the most commonly used character encoding.

<p>True</p> Signup and view all the answers

Unicode was first widely used in the programming language C++.

<p>False</p> Signup and view all the answers

The two main design issues for character string types involve whether they are primitive types or just special kinds of arrays, and the length of objects being static or dynamic.

<p>True</p> Signup and view all the answers

After 1991, the Unicode Consortium developed a 2-byte character code named UCS-2.

<p>False</p> Signup and view all the answers

In C89, all numeric expressions are treated as false if they are nonzero.

<p>False</p> Signup and view all the answers

Python's arrays are called lists and are homogeneous.

<p>False</p> Signup and view all the answers

Ruby supports array catenation.

<p>True</p> Signup and view all the answers

An associative array is an ordered collection of data elements indexed by a single key.

<p>False</p> Signup and view all the answers

In Python, a slice of an array can be referenced as a unit.

<p>True</p> Signup and view all the answers

C-based languages provide various array operations directly.

<p>False</p> Signup and view all the answers

Perl's associative arrays are commonly known as hashes.

<p>True</p> Signup and view all the answers

Python can handle array assignments through value changes only.

<p>False</p> Signup and view all the answers

APLs provide the most basic array processing operations for vectors and matrices.

<p>False</p> Signup and view all the answers

The value nil can be used to reference any memory cell.

<p>False</p> Signup and view all the answers

Dereferencing in C++ is performed using the (*) operator as a prefix unary operation.

<p>True</p> Signup and view all the answers

Type checking ensures that operands of an operator are of compatible types.

<p>True</p> Signup and view all the answers

In Java, if an int is added to a float, the float is coerced to an int.

<p>False</p> Signup and view all the answers

Static type checking can only be performed if type bindings are dynamic.

<p>False</p> Signup and view all the answers

In C++, record elements can be referenced by indices.

<p>False</p> Signup and view all the answers

A tuple in Python is a mutable data type.

<p>False</p> Signup and view all the answers

COBOL uses level numbers to indicate the hierarchical structure of records.

<p>True</p> Signup and view all the answers

List elements in Python can only be of the same type.

<p>False</p> Signup and view all the answers

In Python, tuples can be deleted using the 'del' statement.

<p>False</p> Signup and view all the answers

The PICTURE clause in COBOL specifies the formats of field storage locations.

<p>True</p> Signup and view all the answers

Pointer types in programming may consist only of variable values.

<p>False</p> Signup and view all the answers

In Python, lists are indexed starting from one.

<p>False</p> Signup and view all the answers

What comprises the value of a complex number in programming languages that support it?

<p>One float representing the real part and another for the imaginary part.</p> Signup and view all the answers

What is a significant advantage of using decimal types in programming?

<p>They provide accuracy in decimal values.</p> Signup and view all the answers

In the context of Boolean types, which expression would be considered true in C89?

<p>Any nonzero value from numeric expressions.</p> Signup and view all the answers

What coding standard did Java first adopt for character representation?

<p>16-bit Unicode coding.</p> Signup and view all the answers

Which statement correctly describes character string types?

<p>They are defined by a sequence of characters.</p> Signup and view all the answers

What is a disadvantage of decimal types in programming?

<p>They can waste memory due to fixed decimal point representation.</p> Signup and view all the answers

How is a Boolean value typically represented in memory?

<p>In a single bit, but often stored in a byte.</p> Signup and view all the answers

Which character coding standard was developed after 1991 and could represent four bytes?

<p>UTF-32 (UCS-4).</p> Signup and view all the answers

Which type of array allows its subscript ranges to change dynamically during its lifetime?

<p>Heap-Dynamic Array</p> Signup and view all the answers

What type of array is allocated at elaboration time during execution?

<p>Fixed Stack-Dynamic Array</p> Signup and view all the answers

Which of the following languages allows initialization of arrays at the time of storage allocation?

<p>C++</p> Signup and view all the answers

How many elements will the array declared as 'char name [] = "Freddie";' contain?

<p>8</p> Signup and view all the answers

What character is implicitly added to string arrays in C and C++?

<p>Null character</p> Signup and view all the answers

What is the purpose of using nil in pointer operations?

<p>To indicate that a pointer is not usable</p> Signup and view all the answers

Which operation is performed when accessing a value through a pointer?

<p>Dereferencing</p> Signup and view all the answers

Which characteristic defines a static array?

<p>Statically bound subscript ranges</p> Signup and view all the answers

Which category of array offers fixed subscript ranges with dynamic storage allocation?

<p>Fixed Heap-Dynamic Array</p> Signup and view all the answers

What occurs if an int value is passed to a function expecting a float in C?

<p>A type error is triggered</p> Signup and view all the answers

What are the two fundamental pointer operations mentioned?

<p>Dereferencing and assignment</p> Signup and view all the answers

Which of the following statements is true regarding subscript bindings in arrays?

<p>The subscript type is often a sub-range of integers.</p> Signup and view all the answers

Which of the following statements is true regarding type checking?

<p>Dynamic type checking requires runtime checks</p> Signup and view all the answers

What is the role of a descriptor in programming languages?

<p>To store attributes of variables and support type checking.</p> Signup and view all the answers

Which statement correctly describes floating-point types?

<p>Their representation depends on both precision and range.</p> Signup and view all the answers

What are primitive data types in programming languages?

<p>Basic data types not derived from other types.</p> Signup and view all the answers

What is a defining characteristic of associative arrays?

<p>They are indexed by a unique key.</p> Signup and view all the answers

Which statement about array operations is false?

<p>C-based languages provide many built-in array operations.</p> Signup and view all the answers

Which of the following describes the precision of a floating-point type?

<p>It indicates the accuracy of the fractional part of the value.</p> Signup and view all the answers

Which of the following is NOT a primitive numeric data type in many programming languages?

<p>Character String</p> Signup and view all the answers

In Python, what is the result of slicing the vector with the notation vector(3:6)?

<p>The elements [8, 10, 12]</p> Signup and view all the answers

In many languages, how are unsigned integer types characterized?

<p>They store integer values without signs.</p> Signup and view all the answers

Which of the following languages supports associative arrays under a different name?

<p>Perl refers to them as hashes.</p> Signup and view all the answers

Which of the following operations is NOT typically supported for arrays in C-based languages?

<p>Slicing to get a sub-array.</p> Signup and view all the answers

Which statement about type constructors is true?

<p>They allow combining existing types into new data types.</p> Signup and view all the answers

What happens when dynamic attributes are used in programming?

<p>Descriptors may be required at both compile time and runtime.</p> Signup and view all the answers

What does the notation 'mat[0:2]' return in Python?

<p>The first and second rows of mat.</p> Signup and view all the answers

How are array assignments handled in Python?

<p>They change the references of the objects.</p> Signup and view all the answers

Which programming language offers the most advanced array processing operations?

<p>APL.</p> Signup and view all the answers

What distinguishes a record from an array in programming?

<p>Fields in a record are identified by names, not indices.</p> Signup and view all the answers

In COBOL, what do the level numbers (e.g., 01, 02, 05) indicate?

<p>The hierarchical structure of the record.</p> Signup and view all the answers

Which statement about tuples in Python is correct?

<p>Elements of a tuple can be accessed using indexing.</p> Signup and view all the answers

What is true regarding Python lists compared to tuples?

<p>Lists utilize indexing, similar to tuples.</p> Signup and view all the answers

How are elements deleted from a list in Python?

<p>Using the del statement.</p> Signup and view all the answers

Which of the following accurately describes a pointer type?

<p>It can reference both memory addresses and a nil value.</p> Signup and view all the answers

When constructing a record in COBOL, what do PICTURE clauses specify?

<p>The allowable format of the field's data.</p> Signup and view all the answers

How are elements in a tuple accessed?

<p>By using zero-based indexing in brackets.</p> Signup and view all the answers

Study Notes

CIS217 - Concepts of Programming Languages - Chapter 6 - Data Types

  • A data type defines a collection of data values and a set of operations on those values
  • Computer programs produce results by manipulating data
  • A descriptor collects the attributes of a variable
  • Descriptors are collections of memory cells storing variable attributes
  • Static descriptors are needed only at compile time
  • Dynamic descriptors are maintained during execution
  • Descriptors are used for type checking and allocation/deallocation
  • Primitive data types aren't defined in terms of other types
  • Most programming languages have a set of primitive data types
  • Primitive data types are used along with type constructors

6.2 Primitive Data Types

  • Numeric Types
    • Integers are the most common numeric type
    • Hardware supports various integer sizes (e.g., byte, short, int, long in Java; different sizes in other languages)
    • C++ and C# include unsigned integer types
    • Floating-point types model real numbers (approximations)
    • Scientific languages often support float and double
    • Precision is the accuracy of the fractional part (measured in bits)
    • Range is the range of fractions and exponents
    • Complex numbers are supported in some languages (e.g., Fortran, Python)
    • Literals: (7 + 3j) in Python (real part 7, imaginary part 3)
    • Decimal types store a fixed number of decimal digits (e.g., with decimal point in a fixed position)
    • Advantages: accuracy for decimal values
    • Disadvantages: limited range and wasted memory (compared to floating-point)
  • Boolean Types
    • Represent switched and flags in programs
    • Usually one value for true and one for false (typically 0 and 1, but with corresponding meanings)
  • Character Types
    • Stored as numeric codes (ASCII, Unicode)
    • ASCII is an 8-bit code
    • Unicode (UCS-2, UTF-32) are 16-bit and 4-byte codes respectively (e.g. ISO/IEC 10646 Standard)

6.3 Character String Types

  • Character string types contain sequences of characters
  • Design issues include whether it's a primitive type or specialized array
  • String lengths can be static or dynamic (static length strings set at creation; dynamic length strings allow varying length)

6.4 Enumeration Types

  • Create named constants, grouping collections of values (e.g., days of the week)
  • Enum constants often get implicit integer values; however, explicit values are permitted

6.5 Array Types

  • Arrays are homogeneous aggregates of elements
  • Elements are identified by their position (index)
  • Individual elements have the same type.
  • References to elements use subscript expressions.
  • Variables in subscript expressions require runtime calculations
  • Indexing (or subscripting) maps indices to elements in arrays
  • C uses square brackets [] to specify array indices (e.g. array_name[index_value_list])
  • Array elements and indices have different types (e.g., index type integer)

6.6 Associative Arrays

  • An unordered collection of data elements indexed by keys
  • Each element is a key-value pair
  • Often called "hashes" in some languages (e.g., Perl; dictionaries in Python)

6.7 Record Types

  • Records are aggregates of possibly heterogeneous elements
  • Elements are identified by names (not positions)
  • C, C++, and C# use structs (similar to classes)
  • COBOL uses level numbers to indicate nested records within hierarchy

6.8 Tuple Types

  • Similar to records but elements are not named
  • Elements in tuples are often accessed by their position (index)
  • Tuples are typically immutable in Python (but can be converted to mutable lists)

6.9 List Types

  • Lists, frequently used in functional languages, can have elements of varying types
  • Similar to arrays but often mutable (mutable means their elements can be modified after initial construction)
  • Element access is through indices

6.10 Pointer and Reference Types

  • Variables hold memory addresses
  • nil is a special value to show no valid address
  • Used for dynamic memory management (allocating and deallocating memory space) and indirect addressing.
  • Important for dynamic data structures, passing data to functions, and sharing data across modules
  • Pointers introduce potential dangers of dangling pointers (pointers to memory no longer allocated) and memory leaks.

6.11 Type Checking

  • Verifies compatibility of operator operands
  • Implicit conversions (coercion) are allowed under language rules
  • Errors detected during compile time often referred to as static checking
  • Run-time checks are often necessary for dynamic type bindings.

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This quiz covers various concepts related to data types and arrays in programming languages like Java, C++, and C#. Explore primitive and floating-point types, array types and their characteristics, as well as type checking and memory allocation nuances.

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