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C - Entwicklung String-Funktionen: Zeichen ReadOnly Homepage von PS-Trainer - C-Entwicklung - Strings - an PS-Trainer |
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C - Entwicklung String-Funktionen: Zeichen ReadOnly Homepage von PS-Trainer - C-Entwicklung - Strings - an PS-Trainer |
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| Strings & characters | Overview |
| is, isw Routines | These routines test characters for specified conditions. |
| memchr | Finds characters in a buffer. |
| strchr, wcschr, _mbschr | Find a character in a string. |
| strpbrk, wcspbrk, _mbspbrk | Scan strings for characters in specified character sets. |
| strrchr, wcsrchr, _mbsrchr | Scan a string for the last occurrence of a character. |
| is, isw Routines These routines test characters for specified conditions.
Remarks These routines test characters for specified conditions. The is routines produce meaningful results for any integer argument from –1 (EOF) to UCHAR_MAX (0xFF), inclusive. The expected argument type is int. Warning For the is routines, passing an argument of type char may yield unpredictable results. An SBCS or MBCS single-byte character of type char with a value greater than 0x7F is negative. If a char is passed, the compiler may convert the value to a signed int or a signed long. This value may be sign-extended by the compiler, with unexpected results. The isw routines produce meaningful results for any integer value from – 1 (WEOF) to 0xFFFF, inclusive. The wint_t data type is defined in WCHAR.H as an unsigned short; it can hold any wide character or the wide-character end-of-file (WEOF) value. For each of the these routines, the result of the test for the specified condition depends on the LC_CTYPE category setting of the current locale; see setlocale for more information. In the "C" locale, the test conditions for the is routines are as follows:
Subject: Character Classification Routines | Locale Routines Keywords: See also setlocale, to Function Overview |
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Example * Editor's note: the following
output is significantly #include <stdio.h> void main( void ) |
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| memchr Finds characters in a buffer. void *memchr( const void *buf, int c, size_t count );
Remarks The memchr function looks for the first occurrence of c in the first count bytes of buf. It stops when it finds c or when it has checked the first count bytes. Subject: Buffer Manipulation Routines Keywords: See also _memccpy, memcmp, memcpy, memset, strchr |
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| Return Value If successful, memchr returns a pointer to the first location of c in buf. Otherwise it returns NULL. Parameters
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Example #include <memory.h> int ch = 'r'; void main( void ) printf( "Search char:\t%c\n",
ch ); Search char:
r |
| strchr, wcschr,
_mbschr Find a character in a string. char *strchr( const char *string, int c ); wchar_t *wcschr( const wchar_t *string, wint_t c ); unsigned char *_mbschr( const unsigned char *string, unsigned int c );
Remarks The strchr function finds the first occurrence of c in string, or it returns NULL if c is not found. The null-terminating character is included in the search. wcschr and _mbschr are wide-character and multibyte-character versions of strchr. The arguments and return value of wcschr are wide-character strings; those of _mbschr are multibyte-character strings. _mbschr recognizes multibyte-character sequences according to the multibyte code page currently in use. These three functions behave identically otherwise. Generic-Text Routine Mappings
Subject: String Manipulation Routines Keywords: See also strcspn, strncat, strncmp, strncpy, _strnicmp, strpbrk, strrchr, strstr |
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| Return Value Each of these functions returns a pointer to the first occurrence of c in string, or NULL if c is not found. Parameters
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Example #include <string.h> int ch = 'r'; char string[] = "The quick
brown dog jumps over the lazy fox"; void main( void ) printf( "String to be
searched: \n\t\t%s\n", string ); /* Search forward. */ /* Search backward. */ Search char:
r Result: last r found at position 30 |
| strpbrk, wcspbrk,
_mbspbrk Scan strings for characters in specified character sets. char *strpbrk( const char *string, const char *strCharSet ); wchar_t *wcspbrk( const wchar_t *string, const wchar_t *strCharSet ); unsigned char *_mbspbrk( const unsigned char*string, const unsigned char *strCharSet );
Remarks The strpbrk function returns a pointer to the first occurrence of a character in string that belongs to the set of characters in strCharSet. The search does not include the terminating null character. wcspbrk and _mbspbrk are wide-character and multibyte-character versions of strpbrk. The arguments and return value of wcspbrk are wide-character strings; those of _mbspbrk are multibyte-character strings. These three functions behave identically otherwise. _mbspbrk is similar to _mbscspn except that _mbspbrk returns a pointer rather than a value of type size_t. Generic-Text Routine Mappings
Subject: String Manipulation Routines Keywords: See Also strcspn, strchr, strrchr |
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| Return Value Each of these functions returns a pointer to the first occurrence of any character from strCharSet in string, or a NULL pointer if the two string arguments have no characters in common. Parameters
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Example #include <string.h> void main( void ) 2: 3 men and 2 boys ate 5 pigs 3: 2 boys ate 5 pigs 4: 5 pigs |
| strrchr, wcsrchr,
_mbsrchr Scan a string for the last occurrence of a character. char *strrchr( const char *string, int c ); char *wcsrchr( const wchar_t *string, int c ); int _mbsrchr( const unsigned char *string, unsigned int c );
Remarks The strrchr function finds the last occurrence of c (converted to char) in string. The search includes the terminating null character. wcsrchr and _mbsrchr are wide-character and multibyte-character versions of strrchr. The arguments and return value of wcsrchr are wide-character strings; those of _mbsrchr are multibyte-character strings. These three functions behave identically otherwise. Generic-Text Routine Mappings
Subject: String Manipulation Routines Keywords: See Also strchr, strcspn, _strnicmp, strpbrk, strspn |
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| Return Value Each of these functions returns a pointer to the last occurrence of c in string, or NULL if c is not found. Parameters
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Example #include <string.h> int ch = 'r'; char string[] = "The quick
brown dog jumps over the lazy fox"; void main( void ) printf( "String to be
searched: \n\t\t%s\n", string ); /* Search forward. */ /* Search backward. */ Search char:
r Result: last r found at position 30 |
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