- 01Getting Started
- 02Your First Output (printf)
- 03Working with Variables
- 04Conditionals (if statements)
- 05Loops (for statements)
- 06Writing a Function
- 07Working with Arrays
- 08Loops (while statements)
- 09Working with Structs
- 10Error Handling (Checking a Return Value)
- 11Sorting an Array (Bubble Sort)
- 12Recursive Functions
- 13The String-Handling Standard Library
- 14The switch Statement
- 15The Ternary Operator
- 16Pointer Basics
- 17Writing Comments
- 18Logical Operators (&&, ||, !)
- 19Constants (#define and const)
- 20Splitting Strings (strtok)
- 21Handling NULL Pointers Safely
- 22Searching an Array (Looping with strcmp)
- 23Transforming an Array (map-like Logic)
- 24Two-Dimensional Arrays (Tabular Data)
- 25Custom Errors (Categorizing with Error Codes)
- 26Using Variable-Length Argument Lists (stdarg.h)
- 27Removing Duplicates from an Array (Set-Like Logic)
- 28Checking Correctness with the assert Macro (Your First Step into Testing)
- 29Higher-Order Functions (Passing a Function Pointer as an Argument)
- 30Stacks and Queues (Basic Data Structures)
- 31Type Conversion (Casting) Basics
- 32Intro to Regular Expressions (regex.h)
- 33The Binary Search Algorithm
- 34Building a Caesar Cipher (a Character-Shifting Cipher)
- 35Understanding How Selection Sort Works
- 36Building and Displaying Dates (struct tm)
- 37Writing Multiple Test Cases Together
- 38Speeding Up Calculations with Memoization (Caching)
- 39Normalizing Strings (Stripping Whitespace, Unifying Case)
- 40Shallow Copy vs. Deep Copy
- 41Enum (Enumerated Types) Basics
- 42Flattening an Array
- 43Reversing a String and Checking for Palindromes
- 44Pairing Up Two Arrays (the zip operation)
- 45Rounding Numbers (floor, ceil, round)
- 46Multi-Line Strings (Adjacent String Literal Concatenation)
- 47Functions That Return Multiple Values (Structs)
- 48Finding the GCD and LCM (the Euclidean Algorithm)
- 49Formatting Numbers (Padding Digits, Decimal Places)
- 50Bundling Cleanup Logic with goto
- 51Writing Type-Agnostic Logic with Macros
- 52File Reading and Writing Basics
- 53Generating Random Numbers
- 54Bitwise Operators (AND, OR, XOR, shifts)
- 55Reading Command-Line Arguments
- 56Waiting for a Fixed Amount of Time (sleep)
- 57Watch Out for Floating-Point Rounding Errors
- 58Reading from Standard Input
- 59FizzBuzz (the Classic Practice Problem)
- 60Checking Whether a Number Is Prime
- 61Set Operations with an Array (Intersection, Difference)
- 62Converting Number Bases (Binary, Hex)
- 63Checking Balanced Parentheses (an Application of Stacks)
- 64Checking Whether Two Words Are Anagrams
- 65Checking Whether a Year Is a Leap Year
- 66Converting Temperature (Celsius to Fahrenheit)
- 67Prime Factorization
- 68[Applied] Build a Simple Grade Aggregation Program
Working with Variables
This lesson covers the basics of using variables in C, so you understand explicit, typed variable declarations. It's for anyone searching "C variable tutorial."
A variable is like a "labeled box" that holds a value under a name. Declare one with type variableName = value;. A string is handled as an array of char.
The example declares two variables, char name[] = "Alice" and int age = 14, and builds a message using format specifiers in printf("...%s...%d...", name, age). %s represents a string, and %d represents an integer.
A common early mistake is not realizing C has no dedicated string type โ strings are handled as an array of characters. Since you don't get the convenient string manipulation many other languages offer, you need a deeper understanding of how memory works.
In real projects, staying conscious of a variable's type and the memory size it reserves is the foundation of writing C programs.
๐งช This site can't compile or run C directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser โ nothing is sent anywhere).