EXPRESSION WEEK 2

Question 1

Question: What is the purpose of operators in programming languages?

Answer 1

Answer: Operators in programming languages are used to combine variables and constants into expressions for transforming existing data into new data.

Question 2

Question: What types of operands can be used with operators in programming languages?

Answer 2

Answer: The operands that can be used with operators in programming languages include variables, constants, or other expressions

Question 3

Question: What types of operators are supported in the C language?

Answer 3

Question: What is the data type of a value yielded by a relational expression?

Answer: The value of a relational expression is of type int.

Question 4

Question: What happens when operands of different types are used in an expression?

Answer 4

Answer: This chapter describes what happens when operands of different types are used in an expression, including how to change the type of an operand.

Question 5

Question: What are the hardware components that evaluate expressions?

Answer 5

Answer: The hardware components that evaluate expressions are the ALU and FPA inside the CPU.

Question 6

Question: What expressions can the ALU process on integer types?

Answer 6

Answer: The ALU can process arithmetic, relational, and logical expressions on integer types.

Question 7

Question: What expressions can the FPA process on floating-point types?

Answer 7

Answer: The FPA can process arithmetic, relational, and logical expressions on floating-point types.

Question 8

Question: What are the types of operands used in arithmetic expressions?

Answer 8

Answer: Arithmetic expressions consist of integral operands for processing by the ALU and floating-point operands for processing by the FPA.

Question 9

Question: How many binary and unary arithmetic operations does the C language support on integral operands?

Answer 9

Answer: The C language supports 5 binary and 2 unary arithmetic operations on integral (int and char) operands.

Question 10

Question: What are the binary arithmetic operations on integers and what are their meanings?

Answer 10

Answer: The binary arithmetic operations on integers are addition, subtraction, multiplication, division and remaindering. Their meanings are as follows:

operand + operand: add the operands
operand - operand: subtract the right from the left operand
operand * operand: multiply the operands
operand / operand: divide the left by the right operand. If the division is not exact, the operation discards the remainder and the expression evaluates to the truncated integer result.
operand % operand: remainder of the division of left by right. The expression evaluates to the remainder alone.

Question 11

Question: What are the unary arithmetic operations supported by the C language?

Answer 11

Answer: The unary arithmetic operations supported by the C language are identity and negation, which are represented by the expressions + operand and - operand.

Question 12

Question: What are the binary arithmetic operations on floating-point operands in C?

Answer 12

Answer: The binary arithmetic operations on floating-point operands in C are addition, subtraction, multiplication, and division, which are represented by the expressions operand + operand, operand - operand, operand * operand, and operand / operand.

Question 13

Question: Does the division operator (/) for floating-point operands in C evaluate to a whole number or a floating-point result?

Answer 13

Answer: The division operator (/) for floating-point operands in C evaluates to a floating-point result.

Question 14

Question: What is the purpose of the plus operator in C arithmetic expressions involving unary operations?
.

Answer 14

Answer: The plus operator in C arithmetic expressions involving unary operations is present for language symmetry and leaves the value unchanged

Question 15

Question: What are relational expressions in C language, and how many relational operations does it support?

Answer 15

Answer: Relational expressions in the C language evaluate a condition and compare two values, yielding 1 if the condition is true and 0 if the condition is false. The C language supports 6 relational operations.

Question 16

Question: What is the data type of a value yielded by a relational expression?

Answer 16

Answer: The value of a relational expression is of type int.

Question 17

Question: What are the forms of relational expressions listed in C language, and what do they mean?

Answer 17

Answer: Relational expressions in the C language take one of six forms: operand == operand (operands are equal), operand > operand (left is greater than the right), operand >= operand (left is greater than or equal to the right), operand < operand (left is less than the right), operand <= operand (left is less than or equal to the right), and operand != operand (left is not equal to the right).

Question 18

Question: What types of operands are allowed in relational expressions in C language?

.

Answer 18

Answer: The operands may be integral types or floating-point types

Question 19

Question: What are logical expressions in the C language, and how does it interpret the values true and false?

Answer 19

Answer: Logical expressions in the C language are used to evaluate a condition. The C language does not have reserved words for true or false. It interprets the value 0 as false and any other value as true.

Question 20

Question: What are the three logical operators supported by the C language, and what do they mean?

Answer 20

Answer: The C language supports three logical operators: operand && operand (both operands are true), operand || operand (one of the operands is true), and ! operand (the operand is not true).

Question 21

Question: What is the data type of a value yielded by a logical expression?

Answer 21

Answer: The value of a logical expression is of type int.

Question 22

What is deMorgan’s Law in C programming?

Answer 22

Answer: deMorgan’s Law is a rule that allows the conversion of compound conditions in logical expressions. It states that the opposite of a compound condition is the compound condition with all sub-conditions reversed, all &&’s changed to ||’s and all ||’s to &&’s.

Question 23

What is an example of applying deMorgan’s Law in C programming?

Answer 23

Answer: One example of applying deMorgan’s Law is in defining an adult in C as “!child && !senior”, which is logically equivalent to the expression “!(child || senior)”.

Question 24

What are shorthand assignments in C programming?

Answer 24

Answer: Shorthand assignments are operators that combine an arithmetic expression with an assignment expression in C programming. They store the result of the arithmetic expression in the left operand.

Question 25

What are the binary shorthand assignment operators for integral operands in C programming?

Answer 25

Answer: C programming has 5 binary shorthand assignment operators for integral (int and char) operands. These operators are +=, -=, *=, /=, and %=

Question 26

What is the meaning of the shorthand operator “operand += operand” in C programming?

Answer 26

Answer: The shorthand operator “operand += operand” in C programming is equivalent to the longhand expression “i = i + 4”. It adds 4 to the value of i and assigns the result to i.

Question 27

Question: What are unary operators in C language?

Answer 27

Answer: Unary operators are operators in C language that operate on a single operand. In C language, there are two types of unary operators: prefix and postfix. Prefix operators precede their operands, while postfix operators follow their operands. Examples of unary operators in C language include ++ and –.

Question 28

Question: What is the difference between prefix and postfix expressions in C language?
.

Answer 28

Answer: The main difference between prefix and postfix expressions in C language is in the value of the expression itself. The prefix operator changes the value of its operand and sets the expression’s value to be the changed value. The postfix operator, on the other hand, sets the expression’s value to the operand’s original value and then changes the operand’s value

Question 29

Question: How do prefix and postfix operators work on floating-point operands in C language?

Answer 29

Answer: Prefix and postfix operators operate on floating-point operands in the same way as on integral operands in C language.

Question 30

Question: What are the binary shorthand assignment operators for floating-point operands in C language?

Answer 30

Answer: C language has four binary shorthand assignment operators for floating-point operands, which are: +=, -=, *=, and /=.

Question 31

Question: How can compact use of shorthand operators lead to ambiguity in C language?

Answer 31

Answer: Compact use of shorthand operators can lead to ambiguity in C language across different platforms. For example, in the statement “int j = i++ + i;”, one compiler may increment the first i before the addition, while another compiler may increment i after the addition. To avoid ambiguity, we can re-write the code to make our intent explicit

Question 32

Question: What is casting in C language?

Answer 32

Answer: Casting is a feature in C language that allows us to convert the type of an operand. To convert the type of an operand, we precede the operand with the target type enclosed within parentheses. We call such an expression a cast.

Question 33

Question: What are mixed-type expressions and why do we need rules for converting operands of one type to another type?

Answer 33

Answer: Mixed-type expressions are expressions with operands of different types. CPUs handle expressions with operands of the same type differently. Therefore, we need rules for converting operands of one type to another type to ensure that expressions with operands of different types can be processed by CPUs

Question 34

Question: What is the ranking of types in C language?

Answer 34

Answer: The ranking of types in C language from higher to lower is: long double, double, float, long long, long, int, short, char.

Question 35

Question: What is promotion and truncation in assignment expressions?

Answer 35

Answer: Promotion is the process of converting a lower type operand to a higher type operand when the left operand in an assignment expression is of a higher type than the right operand. Truncation is the process of converting a higher type operand to a lower type operand when the left operand in an assignment expression is of a lower type than the right operand.

Question 36

Question: What happens when C compilers evaluate an arithmetic or relational expression with operands of different types?

Answer 36

Answer: C compilers promote the operand of lower type to an operand of the higher type before evaluating the expression.

Question 37

Question: What are the rules of precedence in evaluating compound expressions in C?

Answer 37

Answer: C compilers evaluate compound expressions according to rules of precedence. The order of precedence, from highest to lowest, and the direction of evaluation are listed in the table below:

Operator Evaluate From
++ – (postfix) left to right
++ – (prefix) + - & ! (all unary) right to left
(type) right to left

/ % left to right
left to right
< <= > >= left to right
== != left to right
&& left to right
|| left to right
= += -= *= /= %= right to left

Question 38

Question: How can we change the order of evaluation in compound expressions?

Answer 38

Answer: We can change the order of evaluation in compound expressions by introducing parentheses. C compilers evaluate the expressions within parentheses before applying the rules of precedence.