strspn

 

C

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Strings library

Null-terminated byte strings

Null-terminated multibyte strings

Null-terminated wide strings

 

Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to and from numeric formats
atoiatolatoll (C99) atof strtolstrtoll (C99) strtoulstrtoull (C99)	strtoimaxstrtoumax (C99)(C99) strtofstrtodstrtold (C99)(C99) strfromfstrfromdstrfroml (C23)(C23)(C23)
String manipulation
strcpystrcpy_s (C11) strncpystrncpy_s (C11) strcatstrcat_s (C11)	strncatstrncat_s (C11) strxfrm strdup (C23) strndup (C23)
String examination
strlenstrnlen_s (C11) strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtokstrtok_s (C11)
Memory manipulation
memchr memcmp memsetmemset_explicitmemset_s (C23)(C11)	memcpymemcpy_s (C11) memmovememmove_s (C11) memccpy (C23)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (C11)(C11)

 

Defined in header <string.h>
size_t strspn(constchar* dest, constchar* src );

Returns the length of the maximum initial segment (span) of the null-terminated byte string pointed to by dest, that consists of only the characters found in the null-terminated byte string pointed to by src.

The behavior is undefined if either dest or src is not a pointer to a null-terminated byte string.

Parameters

dest	-	pointer to the null-terminated byte string to be analyzed
src	-	pointer to the null-terminated byte string that contains the characters to search for

Return value

The length of the maximum initial segment that contains only characters from the null-terminated byte string pointed to by src.

Example

Run this code

#include <stdio.h>#include <string.h>   int main(void){constchar* string ="abcde312$#@";constchar* low_alpha ="qwertyuiopasdfghjklzxcvbnm";   size_t spnsz = strspn(string, low_alpha);printf("After skipping initial lowercase letters from '%s'\n""The remainder is '%s'\n", string, string + spnsz);}

Output:

After skipping initial lowercase letters from 'abcde312$#@' The remainder is '312$#@'

References

• C23 standard (ISO/IEC 9899:2024):

• 7.24.5.6 The strspn function (p: TBD)

• C17 standard (ISO/IEC 9899:2018):

• 7.24.5.6 The strspn function (p: TBD)

• C11 standard (ISO/IEC 9899:2011):

• 7.24.5.6 The strspn function (p: 369)

• C99 standard (ISO/IEC 9899:1999):

• 7.21.5.6 The strspn function (p: 332)

• C89/C90 standard (ISO/IEC 9899:1990):

• 4.11.5.6 The strspn function

See also

strcspn	returns the length of the maximum initial segment that consists of only the characters not found in another byte string (function)
wcsspn (C95)	returns the length of the maximum initial segment that consists of only the wide characters found in another wide string (function)
strpbrk	finds the first location of any character in one string, in another string (function)
C++ documentation for strspn