Challenge Library
Coding Challenges
5,893 curated questions across every arena — browse by topic, then jump into a live 3-minute battle to put them to the test.
Filter by type
Filter by difficulty
Popular topics
5,893 challenges total
- Multiple ChoiceIntermediate
Bitwise AND
cintermediate - Multiple ChoiceIntermediate
Bitwise OR
cintermediate - Multiple ChoiceIntermediate
Bitwise XOR
cintermediate - Multiple ChoiceIntermediate
Left Shift
cintermediate - Multiple ChoiceIntermediate
Right Shift
cintermediate - Multiple ChoiceIntermediate
Bitmask Set
cintermediate - Multiple ChoiceIntermediate
Bitmask Clear
cintermediate - Multiple ChoiceIntermediate
Endianness Big
cintermediate - Multiple ChoiceIntermediate
Endianness Little
cintermediate - Multiple ChoiceIntermediate
volatile Keyword
cintermediate - Multiple ChoiceIntermediate
restrict Keyword
cintermediate - Multiple ChoiceIntermediate
inline Function
cintermediate - Multiple ChoiceIntermediate
assert Macro
cintermediate - Multiple ChoiceIntermediate
errno
cintermediate - Multiple ChoiceIntermediate
perror
cintermediate - Multiple ChoiceIntermediate
atexit
cintermediate - Multiple ChoiceIntermediate
qsort Complexity
cintermediate - Multiple ChoiceIntermediate
bsearch
cintermediate - Multiple ChoiceIntermediate
memcpy vs memmove
cintermediate - Multiple ChoiceIntermediate
memset
cintermediate - Multiple ChoiceIntermediate
Static Library
cintermediate - Multiple ChoiceIntermediate
Dynamic Library
cintermediate - Multiple ChoiceIntermediate
Makefile Target
cintermediate - Multiple ChoiceIntermediate
gcc -Wall
cintermediate - Multiple ChoiceIntermediate
gcc -g
cintermediate - Multiple ChoiceIntermediate
gcc -O2
cintermediate - Multiple ChoiceIntermediate
GDB breakpoint
cintermediate - Multiple ChoiceIntermediate
GDB backtrace
cintermediate - Multiple ChoiceIntermediate
Valgrind Purpose
cintermediate - Multiple ChoiceIntermediate
Sequence Points
cintermediate - Multiple ChoiceIntermediate
Signed Overflow
cintermediate - Multiple ChoiceIntermediate
Null Pointer Deref
cintermediate - Multiple ChoiceIntermediate
Double Free
cintermediate - Multiple ChoiceIntermediate
Use After Free
cintermediate - Multiple ChoiceIntermediate
Stack Overflow
cintermediate - Multiple ChoiceIntermediate
Signal Handler
cintermediate - Multiple ChoiceIntermediate
setjmp/longjmp
cintermediate - Multiple ChoiceBeginner
C: Modulo Operator
cbeginner - Multiple ChoiceBeginner
Address-of Operator
cbeginner - Multiple ChoiceBeginner
Pointer Declaration
cbeginner - Multiple ChoiceBeginner
Dereference Operator
cbeginner - Multiple ChoiceBeginner
NULL Pointer
cbeginner - Multiple ChoiceBeginner
Pointer Size
cbeginner - Multiple ChoiceBeginner
C Strings
cbeginner - Multiple ChoiceBeginner
C: #include
cbeginner - Multiple ChoiceBeginner
C: Entry Point
cbeginner - Multiple ChoiceBeginner
C: Statement Terminator
cbeginner - Multiple ChoiceBeginner
C: char Size
cbeginner - Multiple ChoiceBeginner
C: int Size
cbeginner - Multiple ChoiceBeginner
C: void
cbeginner - Multiple ChoiceBeginner
C: const — Pointer Rules
cbeginner - Multiple ChoiceBeginner
C: Variable Declaration
cbeginner - Code AnalysisHard
Array Decay
code-analysisClanguage - Code AnalysisBeginner
Bitwise AND
code-analysisClanguage - Code AnalysisBeginner
Comma Operator
code-analysisClanguage - Code AnalysisHard
Const Cast
code-analysisClanguage - Code AnalysisHard
Dangling Pointer
code-analysisClanguage - Code AnalysisBeginner
Double to Int
code-analysisClanguage - Code AnalysisIntermediate
Macro Expansion Trap
code-analysisClanguage - Code AnalysisHard
Negative Modulo
code-analysisClanguage
Practice now, dominate the arena
Every challenge here is drawn from the live Code Royale pool. Review a question, then head to the arena to answer under pressure against a real opponent — 3-minute matches, Elo ranking, and badge tiers on the line.