STRLEN(3) | Library Functions Manual | STRLEN(3)

# NAME

`strlen`, `strnlen` — find length of a string

# SYNOPSIS

`#include <string.h>`

size_t
`strlen`(const char *s);

size_t
`strnlen`(const char *s, size_t maxlen);

# DESCRIPTION

The `strlen`() function computes the length of the string s.

The `strnlen`() function computes the length of the string s, up to maxlen characters. The `strnlen`() function will never attempt to address more than maxlen characters, making it suitable for use with character arrays that are not guaranteed to be NUL-terminated.

# RETURN VALUES

The `strlen`() function returns the number of characters that precede the terminating NUL character.

The `strnlen`() function returns the number of characters that precede the terminating NUL or maxlen, whichever is smaller.

# SEE ALSO

wcslen(3)

# STANDARDS

The `strlen`() function conforms to ANSI X3.159-1989 (“ANSI C89”).

The `strlen`() and `strnlen`() functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).

# HISTORY

The `strlen`() function first appeared in Version 6 AT&T UNIX. The `strnlen`() function appeared in glibc 2.0 and was reimplemented for OpenBSD 4.8.

July 31, 2022 | Debian