An enum is a user-defined data type in C that consists of integral constants, providing a way to assign names to these constants for better code readability.
2. How do you define an enum in C?
a) enum { CONST1, CONST2, CONST3 };
b) define enum { CONST1, CONST2, CONST3 };
c) enum [CONST1, CONST2, CONST3];
d) enumeration { CONST1, CONST2, CONST3 };
Answer:
a) enum { CONST1, CONST2, CONST3 };
Explanation:
An enum is defined using the 'enum' keyword followed by a set of named integer constants enclosed in curly braces.
3. What is the default starting value of an enum in C?
a) 1
b) 0
c) -1
d) Depends on the number of elements
Answer:
b) 0
Explanation:
By default, the first item in an enum has a value of 0, and each subsequent item's value is incremented by one from the previous item.
4. Can you assign specific values to enum elements in C?
a) No, enum values are automatically assigned
b) Yes, but only sequential values are allowed
c) Yes, any integer value can be assigned
d) Only positive values can be assigned
Answer:
c) Yes, any integer value can be assigned
Explanation:
In C, specific integer values can be assigned to enum elements. If not assigned, they take on sequential values starting from 0 by default.
5. What is the size of an enum variable in C?
a) The size of a char
b) The size of an int
c) The size of a float
d) The size of a double
Answer:
b) The size of an int
Explanation:
The size of an enum variable in C is typically the same as the size of an int on the host machine.
6. How do you access an element of an enum in C?
a) enumName.elementName
b) elementName
c) enumName[elementName]
d) elementName(enumName)
Answer:
b) elementName
Explanation:
Elements of an enum are accessed directly by their names, which are scoped to the entire program.
7. Can an enum be declared inside a function in C?
a) Yes, in both local and global scope
b) No, enums can only be declared globally
c) Only in the main function
d) Only outside any function
Answer:
a) Yes, in both local and global scope
Explanation:
Enums in C can be declared either inside a function (local scope) or outside of any function (global scope).
8. What happens if two elements in an enum are given the same value?
a) It causes a syntax error
b) It is allowed and both elements represent the same value
c) It causes a runtime error
d) It overwrites the first element with the second
Answer:
b) It is allowed and both elements represent the same value
Explanation:
In C, two elements in an enum can have the same value. This is legal and both elements will represent the same value.
9. Can you compare two enum elements in C?
a) Yes, using the == operator
b) No, enum elements cannot be compared
c) Only if they have the same value
d) Only if they are part of the same enum
Answer:
a) Yes, using the == operator
Explanation:
Enum elements in C can be compared using the equality (==) operator, as they are essentially integer constants.
10. How can enum be used to improve code readability?
a) By replacing numeric constants with meaningful names
b) By using enums as function arguments
c) By creating complex data types
d) Enums cannot improve code readability
Answer:
a) By replacing numeric constants with meaningful names
Explanation:
Enums improve code readability by allowing the use of meaningful names for sets of integer constants, rather than using numeric literals directly.
11. Is it possible to use enums as switch case labels in C?
a) Yes, enum elements can be used as case labels
b) No, switch statements do not accept enums
c) Only if the enum values start from 0
d) Only if the enums are globally declared
Answer:
a) Yes, enum elements can be used as case labels
Explanation:
Enums are often used in switch statements as case labels, providing more readable code compared to using plain integers.
12. What is the default data type of enum elements in C?
a) char
b) int
c) float
d) long
Answer:
b) int
Explanation:
In C, the default data type of enum elements is int.
13. Can you increment an enum element in C?
a) Yes, using the ++ operator
b) No, enum elements are constants and cannot be modified
c) Only within a loop
d) Only if the enum is declared with a specific data type
Answer:
b) No, enum elements are constants and cannot be modified
Explanation:
Enum elements are constants and therefore cannot be incremented or modified in any way after their declaration.
14. How do you typedef an enum in C for easier usage?
a) typedef enumName
b) typedef enum { … } enumName;
c) enum typedef { … } enumName;
d) typedef { enum … } enumName;
Answer:
b) typedef enum { … } enumName;
Explanation:
The 'typedef' keyword can be used with enums to create a new type name, simplifying the declaration of variables of the enum type.
15. Can enums be used to define bitwise operators in C?
a) Yes, but only with specific compiler settings
b) No, enums cannot be used with bitwise operators
c) Yes, enums can be used with bitwise operators
d) Only if the enums are explicitly cast to integers
Answer:
c) Yes, enums can be used with bitwise operators
Explanation:
Enums can be used with bitwise operators in C, as enum values are essentially integers. This is often used in scenarios where enum elements represent bit flags.