CodeBlanks Logo Icon CodeBlanks
Login Register

What is C?

Learn that C is a powerful, low-level systems language and the compilation process.

What is C?

C is a low-level, systems programming language created in 1972 by Dennis Ritchie at Bell Labs. It is still maintained today under the C17 standard.

C is a compiled language: you turn your source code into machine code with a compiler such as gcc. The resulting executable runs directly on the operating system.

C is used for the Linux kernel, embedded systems, compilers and database engines. It excels in any field that needs speed and low memory use.

What can you build with C?

C's power comes from the fields it targets:

  • Operating systems: large parts of the Linux and Windows kernels are written in C
  • Embedded systems: microcontrollers and IoT devices
  • Compilers and interpreters: the reference implementations of Python and PHP are written in C
  • Databases: PostgreSQL and SQLite cores

This versatility makes C worth learning.

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What compiles C source code?

  • chrome
  • javac
  • python
  • gcc Correct answer

Explanation: gcc (GNU Compiler Collection) is a C compiler.

2 Match the concepts

Term Meaning
C Programming language
gcc Compiler
hello.c Source file
a.out Executable

3 Which is NOT suited for C?

  • Build a web frontend Correct answer
  • Write an OS kernel
  • Program an embedded system
  • Write a compiler

Explanation: C is not designed for web frontends; browsers use JavaScript.

4 C level

Question 
C is a ____-level systems language.
Answer 
C is a low-level systems language.

Explanation: C is a low-level systems language.

All lessons in Beginner

1 C basics

  1. What is C?
  2. Your first program
  3. Compile and run
  4. Comments
  5. printf and escapes
  6. Summary - C basics

2 Variables

  1. Declaring variables
  2. Variable assignment
  3. const
  4. Variable scope
  5. typedef
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. char
  4. sizeof
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Menu loop
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Bitwise operators
  6. Summary - Operators

6 I/O

  1. printf formatting
  2. scanf
  3. Multiple inputs
  4. getchar and putchar
  5. puts and fputs
  6. Summary - I/O

7 Conditionals

  1. The if statement
  2. else and else if
  3. The switch statement
  4. The ternary operator
  5. Nested conditionals
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. break and continue
  5. Nested loops
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding products
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Array size
  4. Multidimensional arrays
  5. Arrays and loops
  6. Summary - Arrays

11 Strings

  1. String basics
  2. String literals
  3. strlen
  4. strcpy and strcat
  5. strcmp
  6. Summary - Strings

12 Functions

  1. Defining functions
  2. Return values
  3. Parameters
  4. Function prototypes
  5. Recursion
  6. Summary - Functions

13 Pointer basics

  1. What is a pointer?
  2. The & address operator
  3. Pointer dereference
  4. NULL
  5. Pointer arithmetic
  6. Summary - Pointer basics

14 Arrays and pointers

  1. Array name as pointer
  2. Pointer to array
  3. Passing arrays to functions
  4. Pointer loop
  5. Multidim array pointer
  6. Summary - Arrays and pointers

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String functions

  1. strchr
  2. strstr
  3. strtok
  4. sprintf
  5. sscanf
  6. Summary - String functions

17 Structs

  1. Defining structs
  2. Using structs
  3. typedef struct
  4. Array of structs
  5. Nested structs
  6. Summary - Structs

18 Memory and stack

  1. Stack and heap
  2. Automatic storage
  3. malloc
  4. free
  5. calloc and realloc
  6. Summary - Memory and stack

19 Preprocessor

  1. #define
  2. #include
  3. Conditional compilation
  4. Macro functions
  5. Header files
  6. Summary - Preprocessor

20 Beginner final

  1. Project design
  2. Data model
  3. Functions
  4. Memory management
  5. Putting it together