Standard library header <cstdlib>

 

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Standard library headers

Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header was originally in the C standard library as <stdlib.h>.

This header provides miscellaneous utilities. Symbols defined here are used by several library components.

Macro constants

EXIT_SUCCESSEXIT_FAILURE	indicates program execution status (macro constant)
NULL	implementation-defined null pointer constant (macro constant)
RAND_MAX	maximum possible value generated by std::rand (macro constant)

Types

div_t	structure type, returned by std::div (typedef)
ldiv_t	structure type, returned by std::ldiv (typedef)
lldiv_t (C++11)	structure type, returned by std::lldiv (typedef)
size_t	unsigned integer type returned by the sizeof operator (typedef)

Functions

Process control
abort	causes abnormal program termination (without cleaning up) (function)
exit	causes normal program termination with cleaning up (function)
quick_exit (C++11)	causes quick program termination without completely cleaning up (function)
_Exit (C++11)	causes normal program termination without cleaning up (function)
atexit	registers a function to be called on std::exit() invocation (function)
at_quick_exit (C++11)	registers a function to be called on std::quick_exit invocation (function)
system	calls the host environment's command processor (function)
getenv	access to the list of environment variables (function)
Memory management
malloc	allocates memory (function)
calloc	allocates and zeroes memory (function)
realloc	expands previously allocated memory block (function)
free	deallocates previously allocated memory (function)
Numeric string conversion
atof	converts a byte string to a floating point value (function)
atoiatolatoll (C++11)	converts a byte string to an integer value (function)
strtolstrtoll (C++11)	converts a byte string to an integer value (function)
strtoulstrtoull (C++11)	converts a byte string to an unsigned integer value (function)
strtofstrtodstrtold	converts a byte string to a floating-point value (function)
Wide string manimpulation
mblen	returns the number of bytes in the next multibyte character (function)
mbtowc	converts the next multibyte character to wide character (function)
wctomb	converts a wide character to its multibyte representation (function)
mbstowcs	converts a narrow multibyte character string to wide string (function)
wcstombs	converts a wide string to narrow multibyte character string (function)
Miscellaneous algorithms and math
rand	generates a pseudo-random number (function)
srand	seeds pseudo-random number generator (function)
qsort	sorts a range of elements with unspecified type (function)
bsearch	searches an array for an element of unspecified type (function)
abs(int)labsllabs	computes absolute value of an integral value (|x|) (function)
divldivlldiv	the quotient and remainder of integer division (function)

See Also

• Program support utilities
• Pseudo-random number generation
• Common mathematical functions
• C memory management library
• Null-terminated byte strings
• Null-terminated multibyte strings
• Algorithms library