Unit 4: Data Types & Operators
Contents Guide
1. C Data Types: Range and Size
Data types in C define the type of data a variable can hold and how much space it occupies in memory.
| Data Type | Size (typical) | Range |
|---|---|---|
| char | 1 Byte | -128 to 127 |
| int | 2 or 4 Bytes | -32,768 to 32,767 (for 2 bytes) |
| float | 4 Bytes | 3.4E-38 to 3.4E+38 |
| double | 8 Bytes | 1.7E-308 to 1.7E+308 |
2. Arithmetic & Relational Operators
Arithmetic operators perform mathematical calculations, while relational operators compare values.
Arithmetic Operators
- + (Addition): Adds two operands.
- - (Subtraction): Subtracts the second operand from the first.
- * (Multiplication): Multiplies two operands.
- / (Division): Divides numerator by denominator.
- % (Modulus): Returns the remainder of an integer division.
Relational Operators
Used to check the relationship between two operands. Results are always true (1) or false (0).
- == (Equal to), != (Not equal to).
- > (Greater than), < (Less than).
- >= (Greater than or equal to), <= (Less than or equal to).
3. Logical & Conditional Operators
Logical Operators
Used to combine multiple relational expressions.
- && (Logical AND): True only if both operands are true.
- || (Logical OR): True if at least one operand is true.
- ! (Logical NOT): Reverses the logical state of its operand.
Conditional (Ternary) Operator
Syntax: condition ? value_if_true : value_if_false;
It is the only operator in C that takes three operands.
4. Bitwise & Assignment Operators
Bitwise Operators
These operators perform operations at the bit level (binary).
- & (Bitwise AND), | (Bitwise OR), ^ (Bitwise XOR).
- ~ (Bitwise NOT), << (Left Shift), >> (Right Shift).
Assignment Operators
Used to assign values to variables. C also supports "compound assignment".
- = (Simple Assignment).
- +=, -=, *=, /=, %= (Compound Assignments).
5. Unary vs Binary Operators
Operators are categorized by the number of operands they require.
- Unary Operators: Require only one operand (e.g., ++, --, -, !).
- Binary Operators: Require two operands (e.g., +, -, *, /).
6. Exam Focus Enhancements
- Modulus Rule: The % operator only works with int data types. Using it with float will cause a compile error.
- Division: Remember that integer division (e.g., 5/2) results in 2, not 2.5. To get a decimal, at least one operand must be a float.
- Short-circuit: In Logical AND (&&), if the first expression is false, the second is not even checked.
- = vs ==: Confusing the assignment operator (=) with the equality comparison operator (==) in if statements.
- Range Overflow: Assigning a value larger than 32,767 to a standard 16-bit int.
- Division by Zero: Always ensure the denominator is not zero before performing a division.
Q: What is the size of an int in C?
A: It is compiler-dependent, usually 2 bytes on 16-bit systems and 4 bytes on 32/64-bit systems.
Q: Why do we use Bitwise operators?
A: They are used for low-level programming like device drivers or cryptography where direct bit manipulation is needed.