Keywords in C Last Updated : 30 Aug, 2025 Comments Improve Suggest changes Like Article Like Report Keywords are predefined or reserved words that have special meanings to the compiler. These are part of the syntax and cannot be used as identifiers in the program. A list of keywords in C or reserved words in the C programming language are mentioned below:autobreakcasecharconstcontinuedefaultdodoubleelseenumexternfloatforgotoifintlongregisterreturnshortsignedsizeofstaticstructswitchtypedefunionunsignedvoidvolatilewhileWe cannot use these keywords as identifiers (such as variable names, function names, or struct names). The compiler will throw an error if we try to do so.Example: C #include <stdio.h> int main() { int return = 10; printf("%d\n", return); return 0; } Output./Solution.c: In function 'main':./Solution.c:4:9: error: expected identifier or '(' before 'return' int return = 10; ^./Solution.c:5:20: error: expected expression before 'return' printf("%d\n", return); ^Let's categorize all keywords based on context for a more clear understanding.CategoryKeywords Data Type Keywords char, int, float, double, void, short, long, signed, unsignedOperator & Utility Keywordssizeof, return, goto, typedefControl Flow Keywordsif, else, switch, case, default, for, while, do, break, continueStorage Class Keywordsauto, register, static, externType Qualifiersconst, volatileUser Defined Typesstruct, union, enumDifference Between Keywords and IdentifiersKeywordsIdentifiersReserved Words in C that have a specific meaning and use in the syntaxNames given to variables, functions, structs, etc.Cannot be used as variable names.Can be used as variable names (if not a keyword).Examples: int, return, if, whileExamples: x, total, countPart of the C language grammar.User-defined, meaningful names in the code.Cannot be redefined or repurposed.Can be defined redefined and reused as needed. Comment More infoAdvertise with us K kamleshjoshi18 Follow Improve Article Tags : C Language Explore C Programming Language Tutorial 4 min read C BasicsC Language Introduction 6 min read Features of C Programming Language 3 min read C Programming Language Standard 6 min read C Hello World Program 1 min read Compiling a C Program: Behind the Scenes 4 min read C Comments 3 min read Tokens in C 4 min read Keywords in C 2 min read C Variables and ConstantsC Variables 4 min read Constants in C 4 min read Const Qualifier in C 6 min read Different ways to declare variable as constant in C 2 min read Scope rules in C 5 min read Internal Linkage and External Linkage in C 4 min read Global Variables in C 3 min read C Data TypesData Types in C 5 min read Literals in C 4 min read Escape Sequence in C 5 min read bool in C 5 min read Integer Promotions in C 2 min read Character Arithmetic in C 2 min read Type Conversion in C 4 min read C Input/OutputBasic Input and Output in C 4 min read Format Specifiers in C 5 min read printf in C 5 min read scanf in C 3 min read Scansets in C 2 min read Formatted and Unformatted Input/Output in C 6 min read C OperatorsOperators in C 11 min read Arithmetic Operators in C 5 min read Unary Operators in C 5 min read Relational Operators in C 4 min read Bitwise Operators in C 6 min read C Logical Operators 4 min read Assignment Operators in C 4 min read Increment and Decrement Operators in C 4 min read Conditional or Ternary Operator (?:) in C 3 min read sizeof operator in C 3 min read Operator Precedence and Associativity in C 7 min read C Control Statements Decision-MakingDecision Making in C (if , if..else, Nested if, if-else-if ) 7 min read C - if Statement 4 min read C if else Statement 3 min read C if , else if ladder 4 min read Switch Statement in C 5 min read Using Range in switch Case in C 2 min read C - Loops 6 min read C for Loop 4 min read while Loop in C 5 min read do...while Loop in C 4 min read For vs. While 4 min read Continue Statement in C 4 min read Break Statement in C 5 min read goto Statement in C 4 min read C FunctionsC Functions 6 min read User-Defined Function in C 6 min read Parameter Passing Techniques in C 3 min read Function Prototype in C 4 min read How can I return multiple values from a function? 3 min read main Function in C 5 min read Implicit Return Type int in C 2 min read Callbacks in C 4 min read Nested Functions in C 4 min read Variadic Functions in C 5 min read _Noreturn function specifier in C 2 min read Predefined Identifier __func__ in C 2 min read C Library math.h Functions 6 min read C Arrays & StringsC Arrays 7 min read Properties of Array in C 7 min read Multidimensional Arrays in C - 2D and 3D Arrays 8 min read Initialization of Multidimensional Array in C 4 min read Pass Array to Functions in C 3 min read How to pass a 2D array as a parameter in C? 3 min read What are the data types for which it is not possible to create an array? 2 min read How to pass an array by value in C ? 2 min read Strings in C 6 min read Array of Strings in C 3 min read What is the difference between single quoted and double quoted declaration of char array? 2 min read C String Functions 6 min read C PointersC Pointers 9 min read Pointer Arithmetics in C with Examples 10 min read C - Pointer to Pointer (Double Pointer) 5 min read Function Pointer in C 6 min read How to Declare a Pointer to a Function? 2 min read Pointer to an Array | Array Pointer 5 min read Difference between constant pointer, pointers to constant, and constant pointers to constants 3 min read Pointer vs Array in C 1 min read Dangling, Void , Null and Wild Pointers in C 6 min read Near, Far and Huge Pointers in C 4 min read restrict Keyword in C 3 min read Like