comparison

问题 Looking at Go standard library, there's a ConstantTimeByteEq function that looks like this: func ConstantTimeByteEq(x, y uint8) int { z := ^(x ^ y) z &= z >> 4 z &= z >> 2 z &= z >> 1 return int(z) } Now, I understand the need for constant time string (array, etc.) comparison, as a regular algorithm could short-circuit after the first unequal element. But in this case, isn't a regular comparison of two fixed-sized integers a constant time operation at the CPU level already? 回答1: Not

问题 I'm trying to compare two string lets say Émilie and Zoey. Well 'E' comes before 'Z' but on the ASCII chart Z comes before É so a normal if ( str1 > str2 ) Won't work. I tried with if (strcmp(str1,str2) > 0) still don't work. So i'm looking into a native way to compare string with UTF-8 characters. 回答1: IMPORTANT This answer is meant for situations where it's not possible to run/install the 'intl' extension, and only sorts strings by replacing accented characters to non-accented characters .

问题 I've just been using this code to check if a string is empty: if ($str == "") { // ... } And also the same with the not equals operator... if ($str != "") { // ... } This seems to work (I think), but I'm not sure it's the correct way, or if there are any unforeseen drawbacks. Something just doesn't feel right about it. 回答1: For string comparisons in Perl, use eq or ne : if ($str eq "") { // ... } The == and != operators are numeric comparison operators. They will attempt to convert both

问题 I understand that Apache Thrift and ZeroMQ are softwares belonging to different categories, and it is not easy to do a comparison since it is an apple to orange comparison. But I don't know why they belong to different categories. Aren't they both used to pass data between different services, which may or may not be written in different languages? When should I use Thrift and when should I use a message queue? 回答1: They belong to different categories primarily because they are targetted at

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问题 Both are BDD (Behavior Driven Development) capable unit test frameworks for Scala written in Scala. And Specs is built upon may also involve the ScalaTest framework. But what does Specs offer ScalaTest doesn't? What are the differences? 回答1: Specs and ScalaTest are both good tools with happy users, but they differ in several ways. You will probably want to pick one as your main testing tool in Scala, but need not give up the other because you can use pieces of both. If you like ScalaTest's

问题 I inadvertently typed time.clock<() with the Python 2.7 interpreter response being: True . The following code exemplifies the behavior: >>> repr(time.clock) '<built-in function clock>' >>> time.clock<() True Moreover: >>> import sys >>> sys.maxint < () True >>> map(lambda _:0<_,((),[],{})) [True, True, True] In contrast: >>> 1<set(()) TypeError: can only compare to a set Question: Besides why, is there a practical meaning or purpose of an empty list , tuple or dict evaluating as if were

问题 Write a predicate cmp_list/3 , the first 2 arguments are 2 lists, and the last one is Comparison which means ge , lt , le , or gt . ge : greater or equal lt : less than le : less or equal gt : greater than the output should be like this: the first two lists represent a version of a software, and the function is used to compare two versions of a software to see which one is newer: ?- cmp_list([2,3,4], [2,3,5], C). C = lt ; C = le . ?- cmp_list([1,2,3,4], [1,1,8], C). C = gt ; C = ge . 回答1:

问题 I need git diff functionality for 2 files that I have outside of any repository. Is there a way to do it? Something like git diff --file1 /path/file1.txt --file2 /path/file2.txt If not, what may be an alternative solution? 回答1: The answer is right in the git diff documentation (though I admit it's easy to miss): git diff [<options>] --no-index [--] <path> <path> This form is to compare the given two paths on the filesystem. You can omit the --no-index option when running the command in a

问题 consider the following script: # multipleSmallFrozensets is a list of 7 frozensets of differenet number of string objects multipleSmallFrozensets = [ frozenset({'YHR007C', 'YHR042W'}), frozenset({'YPL274W'}), frozenset({'YCL064C'}), frozenset({'YBR166C'}), frozenset({'YEL041W', 'YJR049C'}), frozenset({'YGL142C'}), frozenset({'YJL134W', 'YKR053C'})] # singleFrozenset is a frozenset of 3410 string objects singleFrozenset = frozenset({'YIL140W','YLR268W','YLR357W','YJL155C','YHR067W', 'YAL008W',