comparison

问题 I have to compare a object with the raw properties of the same class. Meaning, i have to compare those: struct Identifier { string name; string email; } with the two strings name and email. I know i could just create a new Identifier instance for name and email and pass that into equals(). My application has to be very fast and resource-saving. I know that comparison via hashcode isn't a good way, because as explained here there are collisions. But collisions are okay for me, i just need it

问题 I'm not looking for a comparison of two structs that returns bool, I am wondering if there is a way to get which fields of two structs (the same structure, but maybe different values) are different. Basically I want a simpler way to do the following: public class Diff { public String VarName; public object Val1; public object Val2; public Diff(String varName, object val1, object val2) { VarName = varName; Val1 = val1; Val2 = val2; } public override string ToString() { return VarName + "

问题 I have to run a Web server with many services on an embedded server with limited RAM (1 GB, no swap). There will be a maximum of 100 users. I will have services such as a forum, little games (javascript or flash), etc. My team knows Ruby on Rails very well, but I am a bit worried about Rails' memory usage. I really do not want to start a troll here, but I am wondering if there are any serious (i.e. documented) benchmarks comparing Rails, Django, CakePHP or any other PHP framework? Could you

问题 Has anyone used Tokyo Cabinet on the iPhone? I'm interested to see if there are any real world performance differences between it and SQLite3. Also, SQLite 3 has the expressive power of SQL, does Tokyo Cabinet have any kind of query language? Any input would be greatly appreciated, thanks. 回答1: I have not used either on the iPhone specifically, but I have used both for various projects. Like you pointed out, SQLite does provide SQL query language which means you have much more flexibility in

问题 In Java the int type is signed, but it has a method that compares two ints as if they were unsigned: public static int compareUnsigned(int x, int y) { return compare(x + MIN_VALUE, y + MIN_VALUE); } It adds Integer.MIN_VALUE to each argument, then calls the normal signed comparison method, which is: public static int compare(int x, int y) { return (x < y) ? -1 : ((x == y) ? 0 : 1); } How does adding MIN_VALUE to each argument magically make the comparison unsigned? 回答1: This technique works

问题 In F#: > let f x = x + 2;; val f : int -> int > let g x = f x;; val g : int -> int > g 10;; val it : int = 12 > let f x = x + 3;; val f : int -> int > g 10;; val it : int = 12 In Clojure: 1:1 user=> (defn f [x] (+ x 2)) #'user/f 1:2 user=> (defn g [x] (f x)) #'user/g 1:3 user=> (g 10) 12 1:4 user=> (defn f [x] (+ x 3)) #'user/f 1:5 user=> (g 10) 13 Note that in Clojure the most recent version of f gets called in the last line. In F# however still the old version of f is called. Why is this

问题 I've started reading Algorithms and I keep wondering, when dealing with primitives of the same type, which is the more expensive operation, assignment or comparison? Does this vary a great deal between languages? 回答1: Micro-optimization is almost always the wrong thing to do. Don't even start on it unless the program runs too slowly, and you use a profiler to determine exactly where the slow parts are. Once you've done that, my advice is to see about improving code and data locality, because

问题 I got the Json "false" from server. I respond as bool but it's Json so it's in browser type is String instead of bool . So if I run (!data) whenever I want to check "false" == false then they not worked. So how can I parse bool from String in JavaScript then? "true" == true and "false" == false . Then the code (!data) can check what it is [ true and false ] 回答1: I would just explicitly check for the string "true" . let data = value === "true"; Otherwise you could use JSON.parse() to convert

问题 I got the Json "false" from server. I respond as bool but it's Json so it's in browser type is String instead of bool . So if I run (!data) whenever I want to check "false" == false then they not worked. So how can I parse bool from String in JavaScript then? "true" == true and "false" == false . Then the code (!data) can check what it is [ true and false ] 回答1: I would just explicitly check for the string "true" . let data = value === "true"; Otherwise you could use JSON.parse() to convert

问题 lock_percent=$(echo "scale = 5; $value2*100/$value1" | bc) value=`echo "$lock_percent" | bc` if [[ "$value" > "$8" ]]; then echo "Lock Percentage:$value percentage State Critical" exit $STATE_CRITICAL fi I am not able to perform a float comparison with this. I am not able to understand where I am going wrong. 回答1: Bash itself can't use float. In this case maybe you can multiply by 10 or 100 (etc.) and get integer value which you can compare. Or, you can use bc comparison and return value: