using
namespace
std
;
using
std
::
string
;
const
char
*
stristr
(
const
char
*
s1
,
const
char
*
s2
)
{
string ss1
=
_tolower
(
s1
)
;
string ss2
=
_tolower
(
s2
)
;
const
string
::
size_type index
=
ss1
.
find
(
ss2
)
;
if
(
index
==
string
::
npos
)
{
return
NULL
;
}
return
&
s1
[
index
]
;
}