Python Variables & Fundamental Data Types
A variable is a named storage container in computer memory (RAM). Because C++ is statically typed, you must declare the exact type of data a variable will hold before using it: integers (int), decimals (double), single characters (char), truths (bool), or text strings (std::string).
"Think of variables as labeled toolboxes. An "int" box is shaped specifically to hold solid integer bricks. You cannot pour milk (double) into the brick box without causing a mess, and you can't put a book (string) in it either!"
Deep Dive: How It Works
int (Integer): Whole numbers without decimals (e.g. 42, -15, 0). Typically 4 bytes (32 bits).
double & float: Floating-point decimal numbers. double gives 64-bit precision (e.g. 3.14159) and is the default for decimals.
char: A single character enclosed in single quotes (e.g. 'A', '$', '9'). 1 byte.
bool: Boolean truth value (true or false). Typically 1 byte.
std::string: Text string enclosed in double quotes (e.g. "ZenCompiler"). Requires #include <string>.
const: Marks a variable as read-only/immutable (e.g. const double PI = 3.14159;).
Syntax Blueprint
int age = 21; // 4 bytes integer double price = 19.99; // 8 bytes decimal char grade = 'A'; // 1 byte character bool isReady = true; // 1 byte boolean std::string user = "Neo";
Syntax: <type> <variable_name> = <initial_value>;
Core Rules to Remember
Common Beginner Traps & How to Fix Them
Using double quotes for a char: char grade = "A";Why it happens: Treating characters like 1-letter strings.
How to fix: Use single quotes for char: char grade = 'A';.
Live Interactive Example
Hit Run Code to see it liveYour Turn: Micro Challenge
No pressure! Edit the starter code below and test your solution with instant feedback.
Declare an integer and double
- Declare an int variable named fps set to 60.
- Declare a double variable named latency set to 1.5.
- Print "FPS: 60 | Latency: 1.5ms" using these variables.
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