Reference
C Library
IOstream Library
Strings library
STL Containers
STL Algorithms
Miscellaneous
C Library
cassert (assert.h)
cctype (ctype.h)
cerrno (errno.h)
cfloat (float.h)
ciso646 (iso646.h)
climits (limits.h)
clocale (locale.h)
cmath (math.h)
csetjmp (setjmp.h)
csignal (signal.h)
cstdarg (stdarg.h)
cstddef (stddef.h)
cstdio (stdio.h)
cstdlib (stdlib.h)
cstring (string.h)
ctime (time.h)
cstdlib (stdlib.h)
functions:
abort
abs
atexit
atof
atoi
atol
bsearch
calloc
div
exit
free
getenv
labs
ldiv
malloc
mblen
mbstowcs
mbtowc
qsort
rand
realloc
srand
strtod
strtol
strtoul
system
wcstombs
wctomb
functions (non-standard):
itoa
macros:
EXIT_FAILURE
EXIT_SUCCESS
MB_CUR_MAX
NULL
RAND_MAX
types:
div_t
ldiv_t
size_t


size_t

type
<cstdlib>

Unsigned integral type

size_t corresponds to the integer data type returned by the language operator sizeof and is defined in the <cstdlib> header file (among others) as an unsigned integer type.

In <cstlib>, it is used as the type of some parameters in the functions bsearch, qsort, calloc, malloc, realloc, mblen, mbtowc, mbstowcs and wcstombs, and in the case of mbstowcs and wcstombs also as its returning type.
In all cases it is used as a type to represent the length or count in bytes of a specific buffer or string.