D278 QUESTIONS AND VERIFIED SOLUTIONS
What is the purpose of a variable? - ✔✔A variable stores data that can be used and
modified during a program's execution. How do you save a value to a variable? - ✔✔By
using the assignment operator (=), e.g., x = 5. What is a programming expression? - ✔✔A
combination of variables, constants, operators, and functions that evaluates to a value.
What is an identifier? - ✔✔A name used to identify variables, functions, arrays, or other
user-defined elements. What constitutes a valid identifier? - ✔✔Must start with a letter or
underscore, followed by letters, digits, or underscores, and cannot be a keyword. What is a
literal? - ✔✔A fixed value in code, such as 5 or "hello". What is an operator? - ✔✔A symbol
that performs operations on variables and values (e.g., +, -, *, /). What precedence rules
does programming use? - ✔✔Defines the order in which operators are evaluated;
parentheses > multiplication/division > addition/subtraction. How does an integer differ
from a float? - ✔✔Integers are whole numbers; floats contain decimal points. What
happens if you divide two integers? - ✔✔Integer division gives an integer (in some
languages, it truncates). What happens if you divide an integer and a float? -
✔✔Integer/float returns a float. What happens if you divide a nonzero floating point
number by zero? - ✔✔Typically results in infinity or a runtime error, depending on the
language. How do you convert an item's type? - ✔✔Through type casting, like int(), float(),
or str(). What does the modulo operator do? - ✔✔Returns the remainder of a division (e.g.,
5 % 2 = 1). What is the difference in a variable and a constant? - ✔✔A variable's value can
change; a constant's value cannot. How does an array work? - ✔✔Stores multiple values in
indexed positions. What does index reference? - ✔✔The position of an element in an array,
starting at 0. What is the purpose of each different data type? - ✔✔Defines how data is
stored and what operations can be performed on it. How does a branch differ from a loop?
- ✔✔A branch chooses between alternatives; a loop repeats actions. How does an if-else
branch work? - ✔✔Evaluates a condition and runs one block of code if true, another if
false. What does the equality operator do? - ✔✔Compares two values to see if they are
equal; it generally works across most primitive types. What are the four relational
operators? - ✔✔== (equal), != (not equal), < (less than), > (greater than). What are the three
logical operators? - ✔✔&& (and), || (or), ! (not). Explain the precedence rules. - ✔✔NOT (!)
has the highest precedence, followed by AND (&&), then OR (||). How is an infinite loop
created? - ✔✔When a loop's condition never becomes false. What is a sentinel value? -
✔✔A special value that indicates the end of data entry. What are the three parts of a loop?
- ✔✔Initialization, condition, and update. What is the difference in a while loop and
What is the purpose of a variable? - ✔✔A variable stores data that can be used and
modified during a program's execution. How do you save a value to a variable? - ✔✔By
using the assignment operator (=), e.g., x = 5. What is a programming expression? - ✔✔A
combination of variables, constants, operators, and functions that evaluates to a value.
What is an identifier? - ✔✔A name used to identify variables, functions, arrays, or other
user-defined elements. What constitutes a valid identifier? - ✔✔Must start with a letter or
underscore, followed by letters, digits, or underscores, and cannot be a keyword. What is a
literal? - ✔✔A fixed value in code, such as 5 or "hello". What is an operator? - ✔✔A symbol
that performs operations on variables and values (e.g., +, -, *, /). What precedence rules
does programming use? - ✔✔Defines the order in which operators are evaluated;
parentheses > multiplication/division > addition/subtraction. How does an integer differ
from a float? - ✔✔Integers are whole numbers; floats contain decimal points. What
happens if you divide two integers? - ✔✔Integer division gives an integer (in some
languages, it truncates). What happens if you divide an integer and a float? -
✔✔Integer/float returns a float. What happens if you divide a nonzero floating point
number by zero? - ✔✔Typically results in infinity or a runtime error, depending on the
language. How do you convert an item's type? - ✔✔Through type casting, like int(), float(),
or str(). What does the modulo operator do? - ✔✔Returns the remainder of a division (e.g.,
5 % 2 = 1). What is the difference in a variable and a constant? - ✔✔A variable's value can
change; a constant's value cannot. How does an array work? - ✔✔Stores multiple values in
indexed positions. What does index reference? - ✔✔The position of an element in an array,
starting at 0. What is the purpose of each different data type? - ✔✔Defines how data is
stored and what operations can be performed on it. How does a branch differ from a loop?
- ✔✔A branch chooses between alternatives; a loop repeats actions. How does an if-else
branch work? - ✔✔Evaluates a condition and runs one block of code if true, another if
false. What does the equality operator do? - ✔✔Compares two values to see if they are
equal; it generally works across most primitive types. What are the four relational
operators? - ✔✔== (equal), != (not equal), < (less than), > (greater than). What are the three
logical operators? - ✔✔&& (and), || (or), ! (not). Explain the precedence rules. - ✔✔NOT (!)
has the highest precedence, followed by AND (&&), then OR (||). How is an infinite loop
created? - ✔✔When a loop's condition never becomes false. What is a sentinel value? -
✔✔A special value that indicates the end of data entry. What are the three parts of a loop?
- ✔✔Initialization, condition, and update. What is the difference in a while loop and
