C++ Study Guide: Syntax, Variables, Types, and Operators

1. C++ Syntax Fundamentals

C++ syntax defines how programs are written. Mastery of syntax is essential for writing clean, efficient code.

1.1 Structure of a C++ Program

#include <iostream>

using namespace std;

int add(int a, int b);

int main() {
    int result = add(5, 3);
    cout << "Result: " << result << endl;
    return 0;
}

int add(int a, int b) {
    return a + b;
}

#include – includes libraries
using namespace std; – avoids prefixing std::
main() – entry point of the program
Statements end with ;, blocks use {}

1.2 Comments

// Single-line comment
/* Multi-line
   comment */

1.3 Identifiers and Naming Rules

Start with a letter or underscore, followed by letters, digits, or underscores
Case-sensitive: Var ≠ var
Avoid reserved keywords like int, class, return

1.4 Keywords to Know

Category	Keywords
Control	if, else, switch, case, break, continue
Loop	for, while, do
Function	return, void
Object-Oriented	class, struct, public, private, protected, virtual, override
Memory	new, delete
Others	constexpr, const, static, extern, mutable, typename

2. Variables

2.1 Declaration & Initialization

int x = 5;
double pi = 3.1415;
char c = 'A';
bool flag = true;

// Modern C++ (C++11+) uniform initialization
int y{10};
double e{2.718};

2.2 Variable Scope

Local – inside functions, destroyed on exit
Global – outside all functions, lives for program duration
Static – preserves value across function calls

void foo() {
    static int count = 0;
    count++;
    cout << count << endl;
}

2.3 Constants

const int DAYS_IN_WEEK = 7;
constexpr double PI = 3.1415926535; // compile-time constant

3. Types

3.1 Primitive Types

Type	Size (typical)	Example
int	4 bytes	42
short	2 bytes	32000
long	8 bytes	100000L
float	4 bytes	3.14f
double	8 bytes	3.14159
char	1 byte	'A'
bool	1 byte	true/false

3.2 Derived Types

int a = 10;
int* ptr = &a; // pointer
int& ref = a;  // reference
int arr[5] = {1,2,3,4,5};

3.3 User-defined Types

struct Point {
    int x, y;
};

class Rectangle {
    int width, height;
public:
    Rectangle(int w, int h) : width(w), height(h) {}
    int area() { return width * height; }
};

enum Color { RED, GREEN, BLUE };
enum class Shape { CIRCLE, SQUARE, TRIANGLE };

3.4 Type Modifiers

unsigned int u = 10;   // cannot be negative
auto x = 42;              // compiler infers int
auto y = 3.14;            // compiler infers double

4. Operators

4.1 Arithmetic Operators

Operator	Description	Example
+	Addition	2 + 3 → 5
-	Subtraction	5 - 3 → 2
*	Multiplication	4 * 2 → 8
/	Division	8 / 2 → 4
%	Modulus	5 % 2 → 1
++	Increment	i++ or ++i
--	Decrement	i-- or --i

Pre-increment (++i) can be slightly faster than post-increment (i++) in some contexts.

4.2 Comparison Operators

==, !=, <, >, <=, >=

4.3 Logical Operators

&&  // AND
||  // OR
!   // NOT

4.4 Bitwise Operators

&   // AND
|   // OR
^   // XOR
~   // NOT
<< // left shift
>> // right shift

4.5 Assignment Operators

=, +=, -=, *=, /=, %=

4.6 Miscellaneous Operators

condition ? expr1 : expr2   // ternary
sizeof(variable)              // size of variable
static_cast<type>(expr) // type casting

5. Tips for Staff-level Understanding

Know signed vs unsigned integer behavior and overflow
Understand implicit vs explicit type conversions
Practice const-correctness and reference semantics
Be careful with operator precedence and associativity

6. Suggested Practice

Write small programs using all operator types
Play with variable scope and lifetime
Implement structs/classes like Point and Rectangle
Experiment with pointers, references, auto, and constexpr