int sum = 10 + 20;

Token | Type
----- | ----------------------
int   | Keyword
sum   | Identifier
=     | Operator
10    | Literal
+     | Operator
20    | Literal
;     | Separator (Punctuator)

                    C++ Tokens
                        │
 ┌─────────────┬─────────────┬─────────────┬─────────────┐
 │             │             │             │
 ▼             ▼             ▼             ▼
Keywords   Identifiers   Literals     Operators
                        │
                        ▼
                  Punctuators
                  (Separators)

Keyword | Purpose
------- | ---------------------------
int     | Integer data type
float   | Floating-point data type
char    | Character data type
double  | Double-precision data type
bool    | Boolean data type
if      | Conditional statement
else    | Alternative condition
for     | Loop
while   | Loop
return  | Return from a function
class   | Define a class
const   | Declare a constant
void    | No return value

int age = 20;

int studentAge = 18;

// Valid
age
studentName
_total
marks2025

// Invalid
1student
student name
float
total-score

Literal Type   | Example
-------------- | -------
Integer        | 100
Floating-point | 3.14
Character      | 'A'
String         | "Hello"
Boolean        | true

int age = 25;

Operator | Description
-------- | --------------------
+        | Addition
-        | Subtraction
*        | Multiplication
/        | Division
%        | Modulus
=        | Assignment
==       | Equality comparison
&&       | Logical AND
||       | Logical OR

int sum = 10 + 20;

Symbol | Purpose
------ | -------------------------------
;      | Ends a statement
,      | Separates items
{}     | Defines a block of code
()     | Function declaration and calls
[]     | Array indexing

int main()
{
    return 0;
}

#include <iostream>
using namespace std;

int main()
{
    const int age = 20;
    float height = 5.8f;

    cout << "Age: " << age << endl;
    cout << "Height: " << height;

    return 0;
}

const int age = 20;

Token | Category
----- | ----------------
const | Keyword
int   | Keyword
age   | Identifier
=     | Operator
20    | Integer Literal
;     | Punctuator

// Incorrect
int float = 10;

// Correct
int number = 10;