php面試題中常見的騷操作
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$a && $b = $c 表示：如果$a為真，則執(zhí)行$b = $c，否則不執(zhí)行。
可以用if語句替代：
if
(
$a
)
{
$b
=
$c
;
}
其他php7寫法：
$a
=
1
;
$b
=
2
;
$c
=
3
;
$a
?
:
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
1
b
:
2
c
:
3
$a
=
0
;
$b
=
2
;
$c
=
3
;
$a
?
:
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
0
b
:
3
c
:
3
如果$a 為真則執(zhí)行$b 否則不執(zhí)行
return
$a
&&
$b
;
如果$a 為真則執(zhí)行$a=$b 否則不執(zhí)行
$a
&&
$a
=
$b
;
注意：這是種寫法，但在項(xiàng)目里一般是不允許這樣寫，一是這種語法那天不支持了，二是給別人造成閱讀上的障礙，代碼風(fēng)格難以統(tǒng)一.
實(shí)例1：
$a
=
1
;
$b
=
2
;
$c
=
3
;
$a
&&
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
1
b
:
3
c
:
3
實(shí)例2：
$a
=
0
;
$b
=
2
;
$c
=
3
;
$a
&&
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
0
b
:
2
c
:
3
實(shí)例3：
$a
=
1
;
$b
=
0
;
$c
=
3
;
$a
&&
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
1
b
:
3
c
:
3
實(shí)例4：
$a
=
1
;
$b
=
2
;
$c
=
3
;
$a
||
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
1
b
:
2
c
:
3
實(shí)例5：
$a
=
0
;
$b
=
2
;
$c
=
3
;
$a
||
$b
=
$c
;
echo
"a:
$a
"
;
echo
"b:
$b
"
;
echo
"c:
$c
"
;
//輸出是
a
:
0
b
:
3
c
:
3
實(shí)例6：
$a
=
1
;
$b
=
2
;
$c
=
3
;
$d
=
4
;
$e
=
[
'10'
];
$a
&&
$b
&&
$c
!=
$d
&&
$e
[]
=
$c
;
print_r
([
'$a'
=>
$a
,
'$b'
=>
$b
,
'$c'
=>
$c
,
'$d'
=>
$d
,
'$e'
=>
$e
]);
//輸出是
Array
(
[
$a
]
=>
1
[
$b
]
=>
2
[
$c
]
=>
3
[
$d
]
=>
4
[
$e
]
=>
Array
(
[
0
]
=>
10
[
1
]
=>
3
)
)
實(shí)例7：
$a
=
1
;
$b
=
0
;
$c
=
3
;
$d
=
4
;
$e
=
[
'10'
];
$a
&&
$b
&&
$c
!=
$d
&&
$e
[]
=
$c
;
print_r
([
'$a'
=>
$a
,
'$b'
=>
$b
,
'$c'
=>
$c
,
'$d'
=>
$d
,
'$e'
=>
$e
]);
輸出是
Array
(
[
$a
]
=>
1
[
$b
]
=>
0
[
$c
]
=>
3
[
$d
]
=>
4
[
$e
]
=>
Array
(
[
0
]
=>
10
)
)
實(shí)例8：
$a
=
0
;
$b
=
2
;
$c
=
3
;
$d
=
4
;
$e
=
[
'10'
];
$a
&&
$b
&&
$c
!=
$d
&&
$e
[]
=
$c
;
print_r
([
'$a'
=>
$a
,
'$b'
=>
$b
,
'$c'
=>
$c
,
'$d'
=>
$d
,
'$e'
=>
$e
]);
//輸出是
Array
(
[
$a
]
=>
0
[
$b
]
=>
2
[
$c
]
=>
3
[
$d
]
=>
4
[
$e
]
=>
Array
(
[
0
]
=>
10
)
)
實(shí)例9：
$a
=
1
;
$b
=
2
;
$c
=
3
;
$d
=
4
;
$e
=
[
'10'
];
$a
&&
$b
&&
$c
!=
$d
&&
$e
[]
=
$c
;
print_r
([
'$a'
=>
$a
,
'$b'
=>
$b
,
'$c'
=>
$c
,
'$d'
=>
$d
,
'$e'
=>
$e
]);
//輸出是
Array
(
[
$a
]
=>
1
[
$b
]
=>
2
[
$c
]
=>
3
[
$d
]
=>
4
[
$e
]
=>
Array
(
[
0
]
=>
10
[
1
]
=>
3
)
)
實(shí)例10：
$a
=
1
;
$b
=
2
;
$c
=
3
;
$d
=
3
;
$e
=
[
'10'
];
$a
&&
$b
&&
$c
!=
$d
&&
$e
[]
=
$c
;
print_r
([
'$a'
=>
$a
,
'$b'
=>
$b
,
'$c'
=>
$c
,
'$d'
=>
$d
,
'$e'
=>
$e
]);
//輸出是
Array
(
[
$a
]
=>
1
[
$b
]
=>
2
[
$c
]
=>
3
[
$d
]
=>
3
[
$e
]
=>
Array
(
[
0
]
=>
10
)
)
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