NAME
<stdlib.h>: General utilities -
Data Structures
struct div_t
struct ldiv_t
Defines
#define RAND_MAX 0x7FFF
Typedefs
typedef int(* __compar_fn_t )(const void *, const void *)
Functions
void abort (void) __ATTR_NORETURN__
int abs (int __i)
long labs (long __i)
void * bsearch (const void *__key, const void *__base, size_t __nmemb,
size_t __size, int(*__compar)(const void *, const void *))
div_t div (int __num, int __denom) __asm__('__divmodhi4')
ldiv_t ldiv (long __num, long __denom) __asm__('__divmodsi4')
void qsort (void *__base, size_t __nmemb, size_t __size, __compar_fn_t
__compar)
long strtol (const char *__nptr, char **__endptr, int __base)
unsigned long strtoul (const char *__nptr, char **__endptr, int __base)
long atol (const char *__s) __ATTR_PURE__
int atoi (const char *__s) __ATTR_PURE__
void exit (int __status) __ATTR_NORETURN__
void * malloc (size_t __size) __ATTR_MALLOC__
void free (void *__ptr)
void * calloc (size_t __nele, size_t __size) __ATTR_MALLOC__
void * realloc (void *__ptr, size_t __size) __ATTR_MALLOC__
double strtod (const char *__nptr, char **__endptr)
double atof (const char *__nptr)
int rand (void)
void srand (unsigned int __seed)
int rand_r (unsigned long *__ctx)
Variables
size_t __malloc_margin
char * __malloc_heap_start
char * __malloc_heap_end
Non-standard (i.e. non-ISO C) functions.
char * ltoa (long int __val, char *__s, int __radix)
char * utoa (unsigned int __val, char *__s, int __radix)
char * ultoa (unsigned long int __val, char *__s, int __radix)
long random (void)
void srandom (unsigned long __seed)
long random_r (unsigned long *__ctx)
char * itoa (int __val, char *__s, int __radix)
#define RANDOM_MAX 0x7FFFFFFF
Conversion functions for double arguments.
Note that these functions are not located in the default library,
libc.a, but in the mathematical library, libm.a. So when linking the
application, the -lm option needs to be specified.
char * dtostre (double __val, char *__s, unsigned char __prec, unsigned
char __flags)
char * dtostrf (double __val, signed char __width, unsigned char
__prec, char *__s)
#define DTOSTR_ALWAYS_SIGN 0x01
#define DTOSTR_PLUS_SIGN 0x02
#define DTOSTR_UPPERCASE 0x04
Detailed Description
#include <stdlib.h>
This file declares some basic C macros and functions as defined by the
ISO standard, plus some AVR-specific extensions.
Define Documentation
#define DTOSTR_ALWAYS_SIGN 0x01 Bit value that can be passed in flags to
dtostre().
#define DTOSTR_PLUS_SIGN 0x02 Bit value that can be passed in flags to
dtostre().
#define DTOSTR_UPPERCASE 0x04 Bit value that can be passed in flags to
dtostre().
#define RAND_MAX 0x7FFF Highest number that can be generated by rand().
#define RANDOM_MAX 0x7FFFFFFF Highest number that can be generated by
random().
Typedef Documentation
typedef int(* __compar_fn_t)(const void *, const void *) Comparision
function type for qsort(), just for convenience.
Function Documentation
void abort (void) The abort() function causes abnormal program termination
to occur. This realization disables interrupts and jumps to _exit()
function with argument equal to 1. In the limited AVR environment,
execution is effectively halted by entering an infinite loop.
int abs (int __i) The abs() function computes the absolute value of the
integer i.
Note:
The abs() and labs() functions are builtins of gcc.
double atof (const char * nptr) The atof() function converts the initial
portion of the string pointed to by nptr to double representation.
It is equivalent to calling
strtod(nptr, (char **)0);
int atoi (const char * s)
Convert a string to an integer. The atoi() function converts the
initial portion of the string pointed to by s to integer
representation. In contrast to
(int)strtol(s, (char **)NULL, 10);
this function does not detect overflow (errno is not changed and the
result value is not predictable), uses smaller memory (flash and stack)
and works more quickly.
long atol (const char * s)
Convert a string to a long integer. The atol() function converts the
initial portion of the string pointed to by s to long integer
representation. In contrast to
strtol(s, (char **)NULL, 10);
this function does not detect overflow (errno is not changed and the
result value is not predictable), uses smaller memory (flash and stack)
and works more quickly.
void* bsearch (const void * __key, const void * __base, size_t __nmemb,
size_t __size, int(*)(const void *, const void *) __compar) The
bsearch() function searches an array of nmemb objects, the initial
member of which is pointed to by base, for a member that matches the
object pointed to by key. The size of each member of the array is
specified by size.
The contents of the array should be in ascending sorted order according
to the comparison function referenced by compar. The compar routine is
expected to have two arguments which point to the key object and to an
array member, in that order, and should return an integer less than,
equal to, or greater than zero if the key object is found,
respectively, to be less than, to match, or be greater than the array
member.
The bsearch() function returns a pointer to a matching member of the
array, or a null pointer if no match is found. If two members compare
as equal, which member is matched is unspecified.
void* calloc (size_t __nele, size_t __size) Allocate nele elements of size
each. Identical to calling malloc() using nele * size as argument,
except the allocated memory will be cleared to zero.
div_t div (int __num, int __denom) The div() function computes the value
num/denom and returns the quotient and remainder in a structure named
div_t that contains two int members named quot and rem.
char* dtostre (double __val, char * __s, unsigned char __prec, unsigned
char __flags) The dtostre() function converts the double value passed
in val into an ASCII representation that will be stored under s. The
caller is responsible for providing sufficient storage in s.
Conversion is done in the format '[-]d.dddedd' where there is one digit
before the decimal-point character and the number of digits after it is
equal to the precision prec; if the precision is zero, no decimal-point
character appears. If flags has the DTOSTRE_UPPERCASE bit set, the
letter 'E' (rather than 'e' ) will be used to introduce the exponent.
The exponent always contains two digits; if the value is zero, the
exponent is '00'.
If flags has the DTOSTRE_ALWAYS_SIGN bit set, a space character will be
placed into the leading position for positive numbers.
If flags has the DTOSTRE_PLUS_SIGN bit set, a plus sign will be used
instead of a space character in this case.
The dtostre() function returns the pointer to the converted string s.
char* dtostrf (double __val, signed char __width, unsigned char __prec,
char * __s) The dtostrf() function converts the double value passed in
val into an ASCII representationthat will be stored under s. The caller
is responsible for providing sufficient storage in s.
Conversion is done in the format '[-]d.ddd'. The minimum field width of
the output string (including the '.' and the possible sign for negative
values) is given in width, and prec determines the number of digits
after the decimal sign. width is signed value, negative for left
adjustment.
The dtostrf() function returns the pointer to the converted string s.
void exit (int __status) The exit() function terminates the application.
Since there is no environment to return to, status is ignored, and code
execution will eventually reach an infinite loop, thereby effectively
halting all code processing. Before entering the infinite loop,
interrupts are globally disabled.
In a C++ context, global destructors will be called before halting
execution.
void free (void * __ptr) The free() function causes the allocated memory
referenced by ptr to be made available for future allocations. If ptr
is NULL, no action occurs.
char* itoa (int __val, char * __s, int __radix)
Convert an integer to a string. The function itoa() converts the
integer value from val into an ASCII representation that will be stored
under s. The caller is responsible for providing sufficient storage in
s.
Note:
The minimal size of the buffer s depends on the choice of radix.
For example, if the radix is 2 (binary), you need to supply a
buffer with a minimal length of 8 * sizeof (int) + 1 characters,
i.e. one character for each bit plus one for the string terminator.
Using a larger radix will require a smaller minimal buffer size.
Warning:
If the buffer is too small, you risk a buffer overflow.
Conversion is done using the radix as base, which may be a number
between 2 (binary conversion) and up to 36. If radix is greater than
10, the next digit after '9' will be the letter 'a'.
If radix is 10 and val is negative, a minus sign will be prepended.
The itoa() function returns the pointer passed as s.
long labs (long __i) The labs() function computes the absolute value of the
long integer i.
Note:
The abs() and labs() functions are builtins of gcc.
ldiv_t ldiv (long __num, long __denom) The ldiv() function computes the
value num/denom and returns the quotient and remainder in a structure
named ldiv_t that contains two long integer members named quot and rem.
char* ltoa (long int __val, char * __s, int __radix)
Convert a long integer to a string. The function ltoa() converts the
long integer value from val into an ASCII representation that will be
stored under s. The caller is responsible for providing sufficient
storage in s.
Note:
The minimal size of the buffer s depends on the choice of radix.
For example, if the radix is 2 (binary), you need to supply a
buffer with a minimal length of 8 * sizeof (long int) + 1
characters, i.e. one character for each bit plus one for the string
terminator. Using a larger radix will require a smaller minimal
buffer size.
Warning:
If the buffer is too small, you risk a buffer overflow.
Conversion is done using the radix as base, which may be a number
between 2 (binary conversion) and up to 36. If radix is greater than
10, the next digit after '9' will be the letter 'a'.
If radix is 10 and val is negative, a minus sign will be prepended.
The ltoa() function returns the pointer passed as s.
void* malloc (size_t __size) The malloc() function allocates size bytes of
memory. If malloc() fails, a NULL pointer is returned.
Note that malloc() does not initialize the returned memory to zero
bytes.
See the chapter about malloc() usage for implementation details.
void qsort (void * __base, size_t __nmemb, size_t __size, __compar_fn_t
__compar) The qsort() function is a modified partition-exchange sort,
or quicksort.
The qsort() function sorts an array of nmemb objects, the initial
member of which is pointed to by base. The size of each object is
specified by size. The contents of the array base are sorted in
ascending order according to a comparison function pointed to by
compar, which requires two arguments pointing to the objects being
compared.
The comparison function must return an integer less than, equal to, or
greater than zero if the first argument is considered to be
respectively less than, equal to, or greater than the second.
int rand (void) The rand() function computes a sequence of pseudo-random
integers in the range of 0 to RAND_MAX (as defined by the header file
<stdlib.h>).
The srand() function sets its argument seed as the seed for a new
sequence of pseudo-random numbers to be returned by rand(). These
sequences are repeatable by calling srand() with the same seed value.
If no seed value is provided, the functions are automatically seeded
with a value of 1.
In compliance with the C standard, these functions operate on int
arguments. Since the underlying algorithm already uses 32-bit
calculations, this causes a loss of precision. See random() for an
alternate set of functions that retains full 32-bit precision.
int rand_r (unsigned long * __ctx) Variant of rand() that stores the
context in the user-supplied variable located at ctx instead of a
static library variable so the function becomes re-entrant.
long random (void) The random() function computes a sequence of pseudo-
random integers in the range of 0 to RANDOM_MAX (as defined by the
header file <stdlib.h>).
The srandom() function sets its argument seed as the seed for a new
sequence of pseudo-random numbers to be returned by rand(). These
sequences are repeatable by calling srandom() with the same seed value.
If no seed value is provided, the functions are automatically seeded
with a value of 1.
long random_r (unsigned long * __ctx) Variant of random() that stores the
context in the user-supplied variable located at ctx instead of a
static library variable so the function becomes re-entrant.
void* realloc (void * __ptr, size_t __size) The realloc() function tries to
change the size of the region allocated at ptr to the new size value.
It returns a pointer to the new region. The returned pointer might be
the same as the old pointer, or a pointer to a completely different
region.
The contents of the returned region up to either the old or the new
size value (whatever is less) will be identical to the contents of the
old region, even in case a new region had to be allocated.
It is acceptable to pass ptr as NULL, in which case realloc() will
behave identical to malloc().
If the new memory cannot be allocated, realloc() returns NULL, and the
region at ptr will not be changed.
void srand (unsigned int __seed) Pseudo-random number generator seeding;
see rand().
void srandom (unsigned long __seed) Pseudo-random number generator seeding;
see random().
double strtod (const char * nptr, char ** endptr) The strtod() function
converts the initial portion of the string pointed to by nptr to double
representation.
The expected form of the string is an optional plus ( '+' ) or minus
sign ( '-' ) followed by a sequence of digits optionally containing a
decimal-point character, optionally followed by an exponent. An
exponent consists of an 'E' or 'e', followed by an optional plus or
minus sign, followed by a sequence of digits.
Leading white-space characters in the string are skipped.
The strtod() function returns the converted value, if any.
If endptr is not NULL, a pointer to the character after the last
character used in the conversion is stored in the location referenced
by endptr.
If no conversion is performed, zero is returned and the value of nptr
is stored in the location referenced by endptr.
If the correct value would cause overflow, plus or minus INFINITY is
returned (according to the sign of the value), and ERANGE is stored in
errno. If the correct value would cause underflow, zero is returned and
ERANGE is stored in errno.
long strtol (const char * __nptr, char ** __endptr, int __base) The
strtol() function converts the string in nptr to a long value. The
conversion is done according to the given base, which must be between 2
and 36 inclusive, or be the special value 0.
The string may begin with an arbitrary amount of white space (as
determined by isspace()) followed by a single optional '+' or '-' sign.
If base is zero or 16, the string may then include a '0x' prefix, and
the number will be read in base 16; otherwise, a zero base is taken as
10 (decimal) unless the next character is '0', in which case it is
taken as 8 (octal).
The remainder of the string is converted to a long value in the obvious
manner, stopping at the first character which is not a valid digit in
the given base. (In bases above 10, the letter 'A' in either upper or
lower case represents 10, 'B' represents 11, and so forth, with 'Z'
representing 35.)
If endptr is not NULL, strtol() stores the address of the first invalid
character in *endptr. If there were no digits at all, however, strtol()
stores the original value of nptr in endptr. (Thus, if *nptr is not
'\0' but **endptr is '\0' on return, the entire string was valid.)
The strtol() function returns the result of the conversion, unless the
value would underflow or overflow. If no conversion could be performed,
0 is returned. If an overflow or underflow occurs, errno is set to
ERANGE and the function return value is clamped to LONG_MIN or
LONG_MAX, respectively.
unsigned long strtoul (const char * __nptr, char ** __endptr, int __base)
The strtoul() function converts the string in nptr to an unsigned long
value. The conversion is done according to the given base, which must
be between 2 and 36 inclusive, or be the special value 0.
The string may begin with an arbitrary amount of white space (as
determined by isspace()) followed by a single optional '+' or '-' sign.
If base is zero or 16, the string may then include a '0x' prefix, and
the number will be read in base 16; otherwise, a zero base is taken as
10 (decimal) unless the next character is '0', in which case it is
taken as 8 (octal).
The remainder of the string is converted to an unsigned long value in
the obvious manner, stopping at the first character which is not a
valid digit in the given base. (In bases above 10, the letter 'A' in
either upper or lower case represents 10, 'B' represents 11, and so
forth, with 'Z' representing 35.)
If endptr is not NULL, strtoul() stores the address of the first
invalid character in *endptr. If there were no digits at all, however,
strtoul() stores the original value of nptr in endptr. (Thus, if *nptr
is not '\0' but **endptr is '\0' on return, the entire string was
valid.)
The strtoul() function return either the result of the conversion or,
if there was a leading minus sign, the negation of the result of the
conversion, unless the original (non-negated) value would overflow; in
the latter case, strtoul() returns ULONG_MAX, and errno is set to
ERANGE. If no conversion could be performed, 0 is returned.
char* ultoa (unsigned long int __val, char * __s, int __radix)
Convert an unsigned long integer to a string. The function ultoa()
converts the unsigned long integer value from val into an ASCII
representation that will be stored under s. The caller is responsible
for providing sufficient storage in s.
Note:
The minimal size of the buffer s depends on the choice of radix.
For example, if the radix is 2 (binary), you need to supply a
buffer with a minimal length of 8 * sizeof (unsigned long int) + 1
characters, i.e. one character for each bit plus one for the string
terminator. Using a larger radix will require a smaller minimal
buffer size.
Warning:
If the buffer is too small, you risk a buffer overflow.
Conversion is done using the radix as base, which may be a number
between 2 (binary conversion) and up to 36. If radix is greater than
10, the next digit after '9' will be the letter 'a'.
The ultoa() function returns the pointer passed as s.
char* utoa (unsigned int __val, char * __s, int __radix)
Convert an unsigned integer to a string. The function utoa() converts
the unsigned integer value from val into an ASCII representation that
will be stored under s. The caller is responsible for providing
sufficient storage in s.
Note:
The minimal size of the buffer s depends on the choice of radix.
For example, if the radix is 2 (binary), you need to supply a
buffer with a minimal length of 8 * sizeof (unsigned int) + 1
characters, i.e. one character for each bit plus one for the string
terminator. Using a larger radix will require a smaller minimal
buffer size.
Warning:
If the buffer is too small, you risk a buffer overflow.
Conversion is done using the radix as base, which may be a number
between 2 (binary conversion) and up to 36. If radix is greater than
10, the next digit after '9' will be the letter 'a'.
The utoa() function returns the pointer passed as s.
Variable Documentation
char* __malloc_heap_end malloc() tunable.
char* __malloc_heap_start malloc() tunable.
size_t __malloc_margin malloc() tunable.
Author
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Version 1.6.8 Thu Aug 12 201<stdlib.h>: General utilities(3)