这篇文章将讨论如何检查一个特定的值是否已经存在于一个
Dictionary<TKey,TValue>
在 C# 中。
1.使用
Dictionary<TKey,TValue>.ContainsValue()
方法
这
Dictionary<TKey,TValue>
类包含
ContainsValue()
方法，检查它是否包含特定值。它返回一个布尔值来指示该值是否被找到。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
using
System
;
using
System
.
Collections
.
Generic
;
public
class
Example
{
public
static
void
Main
(
)
{
Dictionary
<
string
,
string
>
dict
=
new
Dictionary
<
string
,
string
>
(
)
;
dict
.
Add
(
"White"
,
"#FFFFFF"
)
;
dict
.
Add
(
"Grey"
,
"#808080"
)
;
dict
.
Add
(
"Silver"
,
"#C0C0C0"
)
;
dict
.
Add
(
"Black"
,
"#000000"
)
;
boolean
valueExists
=
dict
.
ContainsValue
(
"#C0C0C0"
)
;
Console
.
WriteLine
(
valueExists
)
;
// True
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
using
System
;
using
System
.
Collections
.
Generic
;
public
class
Example
{
public
static
void
Main
(
)
{
Dictionary
<
string
,
string
>
dict
=
new
Dictionary
<
string
,
string
>
(
)
;
dict
.
Add
(
"White"
,
"#FFFFFF"
)
;
dict
.
Add
(
"Grey"
,
"#808080"
)
;
dict
.
Add
(
"Silver"
,
"#C0C0C0"
)
;
dict
.
Add
(
"Black"
,
"#000000"
)
;
boolean
keyExists
=
dict
.
ContainsValue
(
"Silver"
)
;
Console
.
WriteLine
(
keyExists
)
;
// True
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
using
System
;
using
System
.
Linq
;
using
System
.
Collections
.
Generic
;
public
static
class
Extensions
{
public
static
bool
hasValue
<
K
,
V
>
(
this
IDictionary
<
K
,
V
>
dict
,
V
value
)
{
return
dict
.
Any
(
kvp
=
>
kvp
.
Value
.
Equals
(
value
)
)
;
}
}
public
class
Example
{
public
static
void
Main
(
)
{
Dictionary
<
string
,
string
>
dict
=
new
Dictionary
<
string
,
string
>
(
)
;
dict
.
Add
(
"White"
,
"#FFFFFF"
)
;
dict
.
Add
(
"Grey"
,
"#808080"
)
;
dict
.
Add
(
"Silver"
,
"#C0C0C0"
)
;
dict
.
Add
(
"Black"
,
"#000000"
)
;
boolean
valueExists
=
dict
.
hasValue
(
"#C0C0C0"
)
;
Console
.
WriteLine
(
valueExists
)
;
// True
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
using
System
;
using
System
.
Collections
.
Generic
;
public
static
class
Extensions
{
public
static
bool
hasValue
<
K
,
V
>
(
this
IDictionary
<
K
,
V
>
dict
,
V
value
)
{
foreach
(
KeyValuePair
<
K
,
V
>
kvp
in
dict
)
{
if
(
kvp
.
Value
.
Equals
(
value
)
)
{
return
true
;
}
}
return
false
;
}
}
public
class
Example
{
public
static
void
Main
(
)
{
Dictionary
<
string
,
string
>
dict
=
new
Dictionary
<
string
,
string
>
(
)
;
dict
.
Add
(
"White"
,
"#FFFFFF"
)
;
dict
.
Add
(
"Grey"
,
"#808080"
)
;
dict
.
Add
(
"Silver"
,
"#C0C0C0"
)
;
dict
.
Add
(
"Black"
,
"#000000"
)
;
boolean
valueExists
=
dict
.
hasValue
(
"#C0C0C0"
)
;
Console
.
WriteLine
(
valueExists
)
;
// True
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
using
System
;
using
System
.
Collections
.
Generic
;
public
static
class
Extensions
{
public
static
bool
hasValue
<
K
,
V
>
(
this
IDictionary
<
K
,
V
>
dict
,
V
value
)
{
foreach
(
V
v
in
dict
.
Values
)
{
if
(
v
.
Equals
(
value
)
)
{
return
true
;
}
}
return
false
;
}
}
public
class
Example
{
public
static
void
Main
(
)
{
Dictionary
<
string
,
string
>
dict
=
new
Dictionary
<
string
,
string
>
(
)
;
dict
.
Add
(
"White"
,
"#FFFFFF"
)
;
dict
.
Add
(
"Grey"
,
"#808080"
)
;
dict
.
Add
(
"Silver"
,
"#C0C0C0"
)
;
dict
.
Add
(
"Black"
,
"#000000"
)
;
boolean
valueExists
=
dict
.
hasValue
(
"#C0C0C0"
)
;
Console
.
WriteLine
(
valueExists
)
;
// True
}
}
