C language

 

C

Language

Standard Library

Type support

Dynamic memory management

Error handling

Program utilities

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

 

C language

General topics
Preprocessor
Comments
Keywords
Escape sequences
History of C
Flow control
Conditional execution statements
if statement	switch statement
Iteration statements
for loop	while loop do-while loop
Jump statements
continue statement break statement	goto statement return statement
Functions
function declaration
inline specifier
Types
fundamental types pointer types compound types enumeration types	union types function types
Specifiers
cv specifiers
storage-class specifiers
alignas specifier (C99)
function specifiers (C99)
Literals
integer literals character literals floating-point literals	string literals boolean literals(C99)
Expressions
order of evaluation
operators
operator precedence
alternative operators
Utilities
typedef declaration
attributes (C99)
casts
Miscellaneous
Inline assembly

 

This is a brief reference of available C constructs.

Flow control

Conditional execution statements

Different code paths are executed according to the value of given expression

• if executes code conditionally
• switch executes code according to the value of an integral argument

Iteration statements

The same code is executed several times

• for executes loop
• while executes loop, checking condition before each iteration
• do-while executes loop, checking condition after each iteration

Jump statements

Continue execution at a different location

• continue skips the remaining part of the enclosing loop body
• break terminates the enclosing loop
• goto continues execution in another location
• return terminates execution of the enclosing function

Functions

The same code can be reused at different locations in the program

• function declaration declares a function
• inline specifier hints the compiler to insert a function's body directly into the calling code

Concepts

Scopes of identifiers

Scope determines the visibility of an identifier.

• Function scope
• File scope
• Block scope
• Function prototype scope

Linkages of identifiers

Linkage determines the accessibility of an identifier.

• External linkage
• Internal linkage
• No linkage

Name spaces of identifiers

Name spaces group identifiers around a particular purpose.

Storage durations of objects

Storage duration determines the lifetime of an object.

• Static storage duration
• Thread storage duration
• Automatic storage duration
• Allocated storage duration

Types

Type determines the interpretation of a value.

• basic types define character, integer and floating point types
• array type, contiguously allocated nonempty set of objects with a particular member object type,
• structure type, a sequentially allocated nonempty set of member objects
• union type defines types that can hold data in several representations
• function type defines function call signatures, that is the types of arguments and the return type
• pointer type, holding a memory location
• atomic type, designated by the construct _Atomic
• enumeration type defines types that are able to hold only one of the specified values

Alignment of objects

Data alignment can affect performance.

Conversions

Conversions, implicitly or explicitly, change the value of one data type into a value of another data type.

Arithmetic operands

• Integer conversion rank
• Boolean type
• Signed and unsigned integers
• Real floating and integer
• Real floating types
• Complex types
• Real and complex
• Usual arithmetic conversions

Other operands

• Lvalues, arrays, and function designators
• Void
• Pointers

Declarations

A declaration specifies the interpretation and attributes of a set of identifiers.

Specifiers

• storage-class specifiers specifies storage duration and linkage of a type
• type specifiers specifies the type of a declaration
• function specifiers specifies how the compiler should handle a function (since C99)
• alignment specifier specifies that the storage for the variable should be aligned by specific amount (since C99)

Type Qualifiers

• const type qualifier specifies an object whose value cannot be changed
• volatile type qualifier specifies an object whose value can be change by ways outside the control of the compiler
• restrict type qualifier
• _Atomic type qualifier

Initializers

An initializer specifies the initial value stored in an object.

• default initialization
• arithmetic-type initialization
• pointer-type initialization
• array-type initialization
• struct-type initialization
• union-type initialization

Literals

Literals are the tokens of a C program that represent constant values, embedded in the source code.

• integer literals are decimal, octal, or hexadecimal numbers of integer type.
• character literals are individual characters of type char, char16_t, char32_t, or wchar_t.
• floating-point literals are values of type float, double, or long double
• string literals are sequences of characters, which may be narrow, multibyte, or wide.
• boolean literals are values of type bool, that is true and false (since C99)
• user-defined literals are constant values of user-specified type (since C99)

Expressions

An expression is a sequence of operators and operands that specifies a computation. An expression can result in a value and can cause side effects.

• order of evaluation of arguments and subexpressions specifies the order in which intermediate results are obtained.
• operators allow the use of syntax commonly found in mathematics

Common operators
assignment	increment decrement	arithmetic	logical	comparison	member access	other
a = b a += b a -= b a *= b a /= b a %= b a &= b a |= b a ^= b a <<= b a >>= b	++a --a a++ a--	+a -a a + b a - b a * b a / b a % b ~a a & b a | b a ^ b a << b a >> b	!a a && b a || b	a == b a != b a < b a > b a <= b a >= b	a[b] *a &a a->b a.b	a(...) a, b (type) a ? : sizeof _Alignof (since C11)

• operator precedence is the order in which operators are bound to their arguments
• alternative representations exist for some of the operators

Utilities

Types

• typedef declaration creates a synonym for a type
• attributes defines additional information about variable (since C99)

Casts

• standard conversions implicit conversions from one type to another

Miscellaneous

• main function
• Inline assembly

See also

C++ documentation for C++ language constructs