如何检查词典中是否存在键值对

Question

如何检查字典<>中是否存在键/值对？我能够检查是否存在密钥或值,使用ContainsKey和ContainsValue,但我不确定如何检查密钥/值对是否存在.

谢谢

Answer 1

好了对,如果不能存在关键不存在......所以取与键关联的值,并检查是否这就是你要找的值.例如:

// Could be generic of course, but let's keep things simple...
public bool ContainsKeyValue(Dictionary<string, int> dictionary,
                             string expectedKey, int expectedValue)
{
    int actualValue;
    if (!dictionary.TryGetValue(expectedKey, out actualValue))
    {
        return false;
    }
    return actualValue == expectedValue;
}

或稍微"巧妙"(通常要避免......):

public bool ContainsKeyValue(Dictionary<string, int> dictionary,
                             string expectedKey, int expectedValue)
{
    int actualValue;
    return dictionary.TryGetValue(expectedKey, out actualValue) &&
           actualValue == expectedValue;
}

Answer 2

字典只支持每个键一个值,因此:

// key = the key you are looking for
// value = the value you are looking for
YourValueType found;
if(dictionary.TryGetValue(key, out found) && found == value) {
    // key/value pair exists
}

Answer 3

if (myDic.ContainsKey(testKey) && myDic[testKey].Equals(testValue))
     return true;