.Sh SYNOPSIS
.In stdio.h
.Ft void
-.Fn perror "const char *string"
+.Fo perror
+.Fa "const char *s"
+.Fc
.Vt extern const char * const sys_errlist[] ;
.Vt extern const int sys_nerr ;
.In string.h
.Ft "char *"
-.Fn strerror "int errnum"
+.Fo strerror
+.Fa "int errnum"
+.Fc
.Ft int
-.Fn strerror_r "int errnum" "char *strerrbuf" "size_t buflen"
+.Fo strerror_r
+.Fa "int errnum"
+.Fa "char *strerrbuf"
+.Fa "size_t buflen"
+.Fc
.Sh DESCRIPTION
The
.Fn strerror ,
-.Fn strerror_r
+.Fn strerror_r ,
and
.Fn perror
functions look up the error message string corresponding to an
and writes it, followed by a newline, to the
standard error file descriptor.
If the argument
-.Fa string
+.Fa s
is
.Pf non- Dv NULL
and does not point to the null character,
.Er EINVAL
as a warning.
Error numbers recognized by this implementation fall in
-the range 0 <
+the range 0 <=
.Fa errnum
<
.Fa sys_nerr .