NAME
<string.h>: Strings -
Defines
#define _FFS(x)
Functions
int ffs (int __val)
int ffsl (long __val)
int ffsll (long long __val)
void * memccpy (void *, const void *, int, size_t)
void * memchr (const void *, int, size_t) __ATTR_PURE__
int memcmp (const void *, const void *, size_t) __ATTR_PURE__
void * memcpy (void *, const void *, size_t)
void * memmem (const void *, size_t, const void *, size_t)
__ATTR_PURE__
void * memmove (void *, const void *, size_t)
void * memrchr (const void *, int, size_t) __ATTR_PURE__
void * memset (void *, int, size_t)
int strcasecmp (const char *, const char *) __ATTR_PURE__
char * strcasestr (const char *, const char *) __ATTR_PURE__
char * strcat (char *, const char *)
char * strchr (const char *, int) __ATTR_PURE__
char * strchrnul (const char *, int) __ATTR_PURE__
int strcmp (const char *, const char *) __ATTR_PURE__
char * strcpy (char *, const char *)
size_t strcspn (const char *__s, const char *__reject) __ATTR_PURE__
char * strdup (const char *s1)
size_t strlcat (char *, const char *, size_t)
size_t strlcpy (char *, const char *, size_t)
size_t strlen (const char *) __ATTR_PURE__
char * strlwr (char *)
int strncasecmp (const char *, const char *, size_t) __ATTR_PURE__
char * strncat (char *, const char *, size_t)
int strncmp (const char *, const char *, size_t) __ATTR_PURE__
char * strncpy (char *, const char *, size_t)
size_t strnlen (const char *, size_t) __ATTR_PURE__
char * strpbrk (const char *__s, const char *__accept) __ATTR_PURE__
char * strrchr (const char *, int) __ATTR_PURE__
char * strrev (char *)
char * strsep (char **, const char *)
size_t strspn (const char *__s, const char *__accept) __ATTR_PURE__
char * strstr (const char *, const char *) __ATTR_PURE__
char * strtok (char *, const char *)
char * strtok_r (char *, const char *, char **)
char * strupr (char *)
Detailed Description
#include <string.h>
The string functions perform string operations on NULL terminated
strings.
Note:
If the strings you are working on resident in program space
(flash), you will need to use the string functions described in
<avr/pgmspace.h>: Program Space Utilities.
Define Documentation
#define _FFS(x) This macro finds the first (least significant) bit set in
the input value.
This macro is very similar to the function ffs() except that it
evaluates its argument at compile-time, so it should only be applied to
compile-time constant expressions where it will reduce to a constant
itself. Application of this macro to expressions that are not constant
at compile-time is not recommended, and might result in a huge amount
of code generated.
Returns:
The _FFS() macro returns the position of the first (least
significant) bit set in the word val, or 0 if no bits are set. The
least significant bit is position 1. Only 16 bits of argument are
evaluted.
Function Documentation
int ffs (int val)
This function finds the first (least significant) bit set in the input
value. Returns:
The ffs() function returns the position of the first (least
significant) bit set in the word val, or 0 if no bits are set. The
least significant bit is position 1.
Note:
For expressions that are constant at compile time, consider using
the _FFS macro instead.
int ffsl (long __val)
Same as ffs(), for an argument of type long.
int ffsll (long long __val)
Same as ffs(), for an argument of type long long.
void * memccpy (void * dest, const void * src, int val, size_t len)
Copy memory area. The memccpy() function copies no more than len bytes
from memory area src to memory area dest, stopping when the character
val is found.
Returns:
The memccpy() function returns a pointer to the next character in
dest after val, or NULL if val was not found in the first len
characters of src.
void * memchr (const void * src, int val, size_t len)
Scan memory for a character. The memchr() function scans the first len
bytes of the memory area pointed to by src for the character val. The
first byte to match val (interpreted as an unsigned character) stops
the operation.
Returns:
The memchr() function returns a pointer to the matching byte or
NULL if the character does not occur in the given memory area.
int memcmp (const void * s1, const void * s2, size_t len)
Compare memory areas. The memcmp() function compares the first len
bytes of the memory areas s1 and s2. The comparision is performed using
unsigned char operations.
Returns:
The memcmp() function returns an integer less than, equal to, or
greater than zero if the first len bytes of s1 is found,
respectively, to be less than, to match, or be greater than the
first len bytes of s2.
Note:
Be sure to store the result in a 16 bit variable since you may get
incorrect results if you use an unsigned char or char due to
truncation.
Warning:
This function is not -mint8 compatible, although if you only care
about testing for equality, this function should be safe to use.
void * memcpy (void * dest, const void * src, size_t len)
Copy a memory area. The memcpy() function copies len bytes from memory
area src to memory area dest. The memory areas may not overlap. Use
memmove() if the memory areas do overlap.
Returns:
The memcpy() function returns a pointer to dest.
void * memmem (const void * s1, size_t len1, const void * s2, size_t len2)
The memmem() function finds the start of the first occurrence of the
substring s2 of length len2 in the memory area s1 of length len1.
Returns:
The memmem() function returns a pointer to the beginning of the
substring, or NULL if the substring is not found. If len2 is zero,
the function returns s1.
void * memmove (void * dest, const void * src, size_t len)
Copy memory area. The memmove() function copies len bytes from memory
area src to memory area dest. The memory areas may overlap.
Returns:
The memmove() function returns a pointer to dest.
void * memrchr (const void * src, int val, size_t len) The memrchr()
function is like the memchr() function, except that it searches
backwards from the end of the len bytes pointed to by src instead of
forwards from the front. (Glibc, GNU extension.)
Returns:
The memrchr() function returns a pointer to the matching byte or
NULL if the character does not occur in the given memory area.
void * memset (void * dest, int val, size_t len)
Fill memory with a constant byte. The memset() function fills the first
len bytes of the memory area pointed to by dest with the constant byte
val.
Returns:
The memset() function returns a pointer to the memory area dest.
int strcasecmp (const char * s1, const char * s2)
Compare two strings ignoring case. The strcasecmp() function compares
the two strings s1 and s2, ignoring the case of the characters.
Returns:
The strcasecmp() function returns an integer less than, equal to,
or greater than zero if s1 is found, respectively, to be less than,
to match, or be greater than s2. A consequence of the ordering used
by strcasecmp() is that if s1 is an initial substring of s2, then
s1 is considered to be 'less than' s2.
char * strcasestr (const char * s1, const char * s2) The strcasestr()
function finds the first occurrence of the substring s2 in the string
s1. This is like strstr(), except that it ignores case of alphabetic
symbols in searching for the substring. (Glibc, GNU extension.)
Returns:
The strcasestr() function returns a pointer to the beginning of the
substring, or NULL if the substring is not found. If s2 points to a
string of zero length, the function returns s1.
char * strcat (char * dest, const char * src)
Concatenate two strings. The strcat() function appends the src string
to the dest string overwriting the '\0' character at the end of dest,
and then adds a terminating '\0' character. The strings may not
overlap, and the dest string must have enough space for the result.
Returns:
The strcat() function returns a pointer to the resulting string
dest.
char * strchr (const char * src, int val)
Locate character in string. The strchr() function returns a pointer to
the first occurrence of the character val in the string src.
Here 'character' means 'byte' - these functions do not work with wide
or multi-byte characters.
Returns:
The strchr() function returns a pointer to the matched character or
NULL if the character is not found.
char * strchrnul (const char * s, int c) The strchrnul() function is like
strchr() except that if c is not found in s, then it returns a pointer
to the null byte at the end of s, rather than NULL. (Glibc, GNU
extension.)
Returns:
The strchrnul() function returns a pointer to the matched
character, or a pointer to the null byte at the end of s (i.e.,
s+strlen(s)) if the character is not found.
int strcmp (const char * s1, const char * s2)
Compare two strings. The strcmp() function compares the two strings s1
and s2.
Returns:
The strcmp() function returns an integer less than, equal to, or
greater than zero if s1 is found, respectively, to be less than, to
match, or be greater than s2. A consequence of the ordering used by
strcmp() is that if s1 is an initial substring of s2, then s1 is
considered to be 'less than' s2.
char * strcpy (char * dest, const char * src)
Copy a string. The strcpy() function copies the string pointed to by
src (including the terminating '\0' character) to the array pointed to
by dest. The strings may not overlap, and the destination string dest
must be large enough to receive the copy.
Returns:
The strcpy() function returns a pointer to the destination string
dest.
Note:
If the destination string of a strcpy() is not large enough (that
is, if the programmer was stupid/lazy, and failed to check the size
before copying) then anything might happen. Overflowing fixed
length strings is a favourite cracker technique.
size_t strcspn (const char * s, const char * reject) The strcspn() function
calculates the length of the initial segment of s which consists
entirely of characters not in reject.
Returns:
The strcspn() function returns the number of characters in the
initial segment of s which are not in the string reject. The
terminating zero is not considered as a part of string.
char * strdup (const char * s1)
Duplicate a string. The strdup() function allocates memory and copies
into it the string addressed by s1, including the terminating null
character.
Warning:
The strdup() function calls malloc() to allocate the memory for the
duplicated string! The user is responsible for freeing the memory
by calling free().
Returns:
The strdup() function returns a pointer to the resulting string
dest. If malloc() cannot allocate enough storage for the string,
strdup() will return NULL.
Warning:
Be sure to check the return value of the strdup() function to make
sure that the function has succeeded in allocating the memory!
size_t strlcat (char * dst, const char * src, size_t siz)
Concatenate two strings. Appends src to string dst of size siz (unlike
strncat(), siz is the full size of dst, not space left). At most siz-1
characters will be copied. Always NULL terminates (unless siz <=
strlen(dst)).
Returns:
The strlcat() function returns strlen(src) + MIN(siz,
strlen(initial dst)). If retval >= siz, truncation occurred.
Appends src to string dst of size siz (unlike strncat(), siz is the
full size of dst, not space left). At most siz-1 characters will be
copied. Always NULL terminates (unless siz <= strlen(dst)).
Returns:
The strlcat() function returns strlen(src) + MIN(siz,
strlen(initial dst)). If retval >= siz, truncation occurred.
size_t strlcpy (char * dst, const char * src, size_t siz)
Copy a string. Copy src to string dst of size siz. At most siz-1
characters will be copied. Always NULL terminates (unless siz == 0).
Returns:
The strlcpy() function returns strlen(src). If retval >= siz,
truncation occurred.
Copy src to string dst of size siz. At most siz-1 characters will be
copied. Always NULL terminates (unless siz == 0).
Returns:
The strlcpy() function returns strlen(src). If retval >= siz,
truncation occurred.
size_t strlen (const char * src)
Calculate the length of a string. The strlen() function calculates the
length of the string src, not including the terminating '\0' character.
Returns:
The strlen() function returns the number of characters in src.
char * strlwr (char * s)
Convert a string to lower case. The strlwr() function will convert a
string to lower case. Only the upper case alphabetic characters [A ..
Z] are converted. Non-alphabetic characters will not be changed.
Returns:
The strlwr() function returns a pointer to the converted string.
int strncasecmp (const char * s1, const char * s2, size_t len)
Compare two strings ignoring case. The strncasecmp() function is
similar to strcasecmp(), except it only compares the first len
characters of s1.
Returns:
The strncasecmp() function returns an integer less than, equal to,
or greater than zero if s1 (or the first len bytes thereof) is
found, respectively, to be less than, to match, or be greater than
s2. A consequence of the ordering used by strncasecmp() is that if
s1 is an initial substring of s2, then s1 is considered to be 'less
than' s2.
char * strncat (char * dest, const char * src, size_t len)
Concatenate two strings. The strncat() function is similar to strcat(),
except that only the first n characters of src are appended to dest.
Returns:
The strncat() function returns a pointer to the resulting string
dest.
int strncmp (const char * s1, const char * s2, size_t len)
Compare two strings. The strncmp() function is similar to strcmp(),
except it only compares the first (at most) n characters of s1 and s2.
Returns:
The strncmp() function returns an integer less than, equal to, or
greater than zero if s1 (or the first n bytes thereof) is found,
respectively, to be less than, to match, or be greater than s2.
char * strncpy (char * dest, const char * src, size_t len)
Copy a string. The strncpy() function is similar to strcpy(), except
that not more than n bytes of src are copied. Thus, if there is no null
byte among the first n bytes of src, the result will not be null-
terminated.
In the case where the length of src is less than that of n, the
remainder of dest will be padded with nulls.
Returns:
The strncpy() function returns a pointer to the destination string
dest.
size_t strnlen (const char * src, size_t len)
Determine the length of a fixed-size string. The strnlen function
returns the number of characters in the string pointed to by src, not
including the terminating '\0' character, but at most len. In doing
this, strnlen looks only at the first len characters at src and never
beyond src+len.
Returns:
The strnlen function returns strlen(src), if that is less than len,
or len if there is no '\0' character among the first len characters
pointed to by src.
char * strpbrk (const char * s, const char * accept) The strpbrk() function
locates the first occurrence in the string s of any of the characters
in the string accept.
Returns:
The strpbrk() function returns a pointer to the character in s that
matches one of the characters in accept, or NULL if no such
character is found. The terminating zero is not considered as a
part of string: if one or both args are empty, the result will
NULL.
char * strrchr (const char * src, int val)
Locate character in string. The strrchr() function returns a pointer to
the last occurrence of the character val in the string src.
Here 'character' means 'byte' - these functions do not work with wide
or multi-byte characters.
Returns:
The strrchr() function returns a pointer to the matched character
or NULL if the character is not found.
char * strrev (char * s)
Reverse a string. The strrev() function reverses the order of the
string.
Returns:
The strrev() function returns a pointer to the beginning of the
reversed string.
char * strsep (char ** sp, const char * delim)
Parse a string into tokens. The strsep() function locates, in the
string referenced by *sp, the first occurrence of any character in the
string delim (or the terminating '\0' character) and replaces it with a
'\0'. The location of the next character after the delimiter character
(or NULL, if the end of the string was reached) is stored in *sp. An
``empty'' field, i.e. one caused by two adjacent delimiter characters,
can be detected by comparing the location referenced by the pointer
returned in *sp to '\0'.
Returns:
The strsep() function returns a pointer to the original value of
*sp. If *sp is initially NULL, strsep() returns NULL.
size_t strspn (const char * s, const char * accept) The strspn() function
calculates the length of the initial segment of s which consists
entirely of characters in accept.
Returns:
The strspn() function returns the number of characters in the
initial segment of s which consist only of characters from accept.
The terminating zero is not considered as a part of string.
char * strstr (const char * s1, const char * s2)
Locate a substring. The strstr() function finds the first occurrence of
the substring s2 in the string s1. The terminating '\0' characters are
not compared.
Returns:
The strstr() function returns a pointer to the beginning of the
substring, or NULL if the substring is not found. If s2 points to a
string of zero length, the function returns s1.
char * strtok (char * s, const char * delim)
Parses the string s into tokens. strtok parses the string s into
tokens. The first call to strtok should have s as its first argument.
Subsequent calls should have the first argument set to NULL. If a token
ends with a delimiter, this delimiting character is overwritten with a
'\0' and a pointer to the next character is saved for the next call to
strtok. The delimiter string delim may be different for each call.
Returns:
The strtok() function returns a pointer to the next token or NULL
when no more tokens are found.
Note:
strtok() is NOT reentrant. For a reentrant version of this function
see strtok_r().
char * strtok_r (char * string, const char * delim, char ** last)
Parses string into tokens. strtok_r parses string into tokens. The
first call to strtok_r should have string as its first argument.
Subsequent calls should have the first argument set to NULL. If a token
ends with a delimiter, this delimiting character is overwritten with a
'\0' and a pointer to the next character is saved for the next call to
strtok_r. The delimiter string delim may be different for each call.
last is a user allocated char* pointer. It must be the same while
parsing the same string. strtok_r is a reentrant version of strtok().
Returns:
The strtok_r() function returns a pointer to the next token or NULL
when no more tokens are found.
char * strupr (char * s)
Convert a string to upper case. The strupr() function will convert a
string to upper case. Only the lower case alphabetic characters [a ..
z] are converted. Non-alphabetic characters will not be changed.
Returns:
The strupr() function returns a pointer to the converted string.
The pointer is the same as that passed in since the operation is
perform in place.
Author
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