comparison-operators

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 6 years ago . I need to analyze a string in JAVA to find out if it has both letters and numbers. So this is what I have so far. The variable pass is a String of maximum 8 characters/numbers that is inputted by the user. if

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 6 years ago . I need to analyze a string in JAVA to find out if it has both letters and numbers. So this is what I have so far. The variable pass is a String of maximum 8 characters/numbers that is inputted by the user. if

问题 The Cython libcpp module contains a template for priority_queue , which is great, except for one thing: I cannot pass it a custom comparer (or, at least, I don't know how to). I need this because I need the priority_queue to do an argsort of sorts rather than a sort (yes, a priority queue is optimal for what I want to do), and I need it to be fast. Is this possible within Cython, perhaps by wrapping a queue in a custom way, or not at all? As an example, say I want to sort a vector[int[:]] by

问题 Beginning programmer here, just wanting to understand the process behind Ruby's sort method when using the spaceship operator <=> . Hope someone can help. In the following: array = [1, 2, 3] array.sort { |a, b| a <=> b } ... I understand that sort is comparing a pair of numbers at a time and then returning -1 if a belongs before b , 0 if they're equal, or 1 if a should follow b . But in the case of sorting in descending order, like so: array.sort { |a, b| b <=> a } ... what exactly is

问题 I wrote a bash script that performs a curl call only during business hours. For some reason, the hourly comparison fails when I add an "-a" operator (and for some reason my bash does not recognize "&&"). Though the script is much larger, here is the relevant piece: HOUR=`date +%k` if [ $HOUR > 7 -a $HOUR < 17 ]; then //do sync fi The script gives me the error: ./tracksync: (last line): Cannot open (line number): No such file However, this comparison does not fail: if [ $DAY != "SUNDAY" -a

问题 I wrote a bash script that performs a curl call only during business hours. For some reason, the hourly comparison fails when I add an "-a" operator (and for some reason my bash does not recognize "&&"). Though the script is much larger, here is the relevant piece: HOUR=`date +%k` if [ $HOUR > 7 -a $HOUR < 17 ]; then //do sync fi The script gives me the error: ./tracksync: (last line): Cannot open (line number): No such file However, this comparison does not fail: if [ $DAY != "SUNDAY" -a

问题 There are many cases in which JavaScript's type-coercing equality operator is not transitive. For example, see "JavaScript equality transitivity is weird." However, are there any cases in which == isn't symmetric ? That is, where a == b is true and b == a is false ? 回答1: In Javascript, == is always symmetric. The spec says: NOTE 2 The equality operators maintain the following invariants: A != B is equivalent to !(A == B) . A == B is equivalent to B == A , except in the order of evaluation of

问题 There are many cases in which JavaScript's type-coercing equality operator is not transitive. For example, see "JavaScript equality transitivity is weird." However, are there any cases in which == isn't symmetric ? That is, where a == b is true and b == a is false ? 回答1: In Javascript, == is always symmetric. The spec says: NOTE 2 The equality operators maintain the following invariants: A != B is equivalent to !(A == B) . A == B is equivalent to B == A , except in the order of evaluation of

问题 Comparing two instances of the following struct, I receive an error: struct MyStruct1 { MyStruct1(const MyStruct2 &_my_struct_2, const int _an_int = -1) : my_struct_2(_my_struct_2), an_int(_an_int) {} std::string toString() const; MyStruct2 my_struct_2; int an_int; }; The error is: error C2678: binary '==' : no operator found which takes a left-hand operand of type 'myproj::MyStruct1' (or there is no acceptable conversion) Why? 回答1: In C++, struct s do not have a comparison operator generated

问题 I have a class called AString . It is pretty basic: class AString { public: AString(const char *pSetString = NULL); ~AString(); bool operator==(const AString &pSetString); ... protected: char *pData; int iDataSize; } Now I want to write code like this: AString *myString = new AString("foo"); if (myString == "bar") { /* and so on... */ } However, the existing comparison operator only supports if (*myString == "bar") If I omit that asterisk, the compiler is unhappy. Is there a way to allow the