strlen(3) Library Functions Manual strlen(3) strlen - (libc -lc) #include size_t strlen(const char *s); strlen() s ('\0'). strnul(s) - s strlen() s. attributes(7). +------------+------------------------------------+--------------------+ || | | +------------+------------------------------------+--------------------+ |strlen() | | MT-Safe | +------------+------------------------------------+--------------------+ C11, POSIX.1-2008. POSIX.1-2001 C89 SVr4 4.3BSD. strnlen(3) . string(3), strnlen(3), strnul(3), wcslen(3), wcsnlen(3) 3 . . : . 6.18 25 2026 strlen(3)