strlen(3)		    Library Functions Manual		       strlen(3)

NAME
     strlen - calculate the length of a string

LIBRARY
     Standard C library (libc, -lc)

SYNOPSIS
     #include <string.h>

     size_t strlen(const char *s);

DESCRIPTION
     The  strlen() function calculates the length of the string pointed to by s,
     excluding the terminating null byte ('\0').

     It is equivalent to

	 strnul(s) - s

RETURN VALUE
     The strlen() function returns the number of bytes in the string pointed  to
     by s.

ATTRIBUTES
     For  an  explanation  of the terms used in this section, see attributes(7).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ strlen() T}	  Thread
     safety  MT-Safe

STANDARDS
     C11, POSIX.1-2008.

HISTORY
     POSIX.1-2001, C89, SVr4, 4.3BSD.

NOTES
     In cases where the input buffer may not contain a	terminating  null  byte,
     strnlen(3) should be used instead.

SEE ALSO
     string(3), strnlen(3), strnul(3), wcslen(3), wcsnlen(3)

Linux man-pages 6.18		   2026-02-25			       strlen(3)