.Sh SYNOPSIS
.In string.h
.Ft size_t
-.Fn strspn "const char *s" "const char *charset"
+.Fo strspn
+.Fa "const char *s1"
+.Fa "const char *s2"
+.Fc
.Sh DESCRIPTION
The
.Fn strspn
function
spans the initial part of the null-terminated string
-.Fa s
+.Fa s1 ,
as long as the characters from
-.Fa s
+.Fa s1
occur in the null-terminated string
-.Fa charset .
+.Fa s2 .
In other words, it computes the string array index in
-.Fa s
+.Fa s1
of the first character of
-.Fa s
+.Fa s1
which is not in
-.Fa charset ,
+.Fa s2 ,
else the index of the first null character.
.Sh RETURN VALUES
The