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strspn(3)
NAME
  strcspn, strspn - Returns length of initial segment of string

LIBRARY
  Standard C Library (libc.so, libc.a)

SYNOPSIS
  #include <string.h>

  size_t strcspn(
	  const char *s1,
	  const char *s2);

  size_t strspn(
	  const char *s1,
	  const char *s2);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  strcspn(), strspn():	XPG4, XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  s1	    Points to a character string being checked for an initial
	    segment.

  s2	    Points to a string containing a set of bytes that define the
	    initial segment.

DESCRIPTION
  The strspn() function computes the length of the maximum initial segment of
  the string pointed to by the s1 parameter, which consists entirely of bytes
  from the string pointed to by the s2 parameter.

  The strcspn() function computes the byte length of the maximum initial
  segment of the string pointed to by the s1 parameter, which consists
  entirely of bytes that are not from the string pointed to by the s2
  parameter.

  The strspn() and strcspn() functions treat the s2 parameter as a series of
  bytes; these functions do not treat a multibyte character as a single unit
  but rather as a series of separate bytes. There are no equivalent functions
  for multibyte character strings. The wcsspn() and wcscspn() functions
  provide the same functionality for wide character strings.

RETURN VALUES
  Upon successful completion, the strcspn(), and strspn() functions return
  the length of the string segment.

  [Digital]  On error, a value of -1 cast to size_t is returned.

RELATED INFORMATION
  Functions: string(3), wcsspn(3)/wcscspn(3)

  Standards: standards(5)