comparison

问题 This issue is simple, but I am not sure what is the best approach to get around it. If the variable contains a number, how can I make sure that the if statement only returns true if indeed the $some_var is one? 回答1: you need to use 3 equals if($some_var ===1){ here is more info http://php.net/manual/en/language.operators.comparison.php 回答2: The number 1 is a shortcut for "true". In order to specify that it must actually be true, you want to use a triple equals operator. This makes sure it

问题 just wondering why duplicated behaves the way it does with NAs: > duplicated(c(NA,NA,NA,1,2,2)) [1] FALSE TRUE TRUE FALSE FALSE TRUE where in fact > NA == NA [1] NA is there a way to achieve that duplicated marks NAs as false, like this? > duplicated(c(NA,NA,NA,1,2,2)) [1] FALSE FALSE FALSE FALSE FALSE TRUE 回答1: You use the argument incomparables for the function duplicated like this : > duplicated(c(NA,NA,NA,1,2,2)) [1] FALSE TRUE TRUE FALSE FALSE TRUE > duplicated(c(NA,NA,NA,1,2,2)

问题 Today I was tracking down why my program was getting some unexpected checksum-mismatch errors, in some code that I wrote that serializes and deserializes IEEE-754 floating-point values, in a format that includes a 32-bit checksum value (which is computed by running a CRC-type algorithm over the bytes of the floating-point array). After a bit of head-scratching, I realized the problem was the 0.0f and -0.0f have different bit-patterns (0x00000000 vs 0x00000080 (little-endian), respectively),

问题 Today I was tracking down why my program was getting some unexpected checksum-mismatch errors, in some code that I wrote that serializes and deserializes IEEE-754 floating-point values, in a format that includes a 32-bit checksum value (which is computed by running a CRC-type algorithm over the bytes of the floating-point array). After a bit of head-scratching, I realized the problem was the 0.0f and -0.0f have different bit-patterns (0x00000000 vs 0x00000080 (little-endian), respectively),

问题 So here's what I understand (please correct if wrong) : HTML5 is the newest version (or at least soon to be released) of HTML and contains features that XHTML does not yet have XHTML served as MIME type text/html is equal to HTML for the purposes of rendering Converting from text/html to application/xhtml+xml is difficult because it's not HTML XML is not compatible with HTML So my question is, what does XHTML have to do with HTML besides the usage of tags? What is the practical purpose of

问题 for i:=0;i<len(a);i++{ if a[i] != b[i]{ return false } } and just a == b I've found that the same string have different address a := "abc" b := "abc" println(&a) println(&b) answer is : 0xc420045f68 0xc420045f58 so == not using address to compare. In fact, I would like to know how == compares two strings. I am searching for a long time on net. But failed... 回答1: You should use the == operator to compare strings. It compares the content of the string values. What you print is the address of a

问题 I have a function which takes two strings and gives out the cosine similarity value which shows the relationship between both texts. If I want to compare 75 texts with each other, I need to make 5,625 single comparisons to have all texts compared with each other. Is there a way to reduce this number of comparisons? For example sparse matrices or k-means? I don't want to talk about my function or about ways to compare texts. Just about reducing the number of comparisons. 回答1: What Ben says it

问题 I have a function which takes two strings and gives out the cosine similarity value which shows the relationship between both texts. If I want to compare 75 texts with each other, I need to make 5,625 single comparisons to have all texts compared with each other. Is there a way to reduce this number of comparisons? For example sparse matrices or k-means? I don't want to talk about my function or about ways to compare texts. Just about reducing the number of comparisons. 回答1: What Ben says it

问题 This is related to one of my previous question: How to compare values of rows and columns of two text files in bash? file1.txt (with special characters: cat -vet file1.txt) Name Col1 Col2 Col3^M$ -----------------------^M$ row1 1 4 7^M$ row2 2 5 8^M$ row3 3 6 9$ file2.txt (with special characters: cat -vet file2.txt) Name Col1 Col2 Col3^M$ -----------------------^M$ row1 1 4 7^M$ row2 2 5 999$ I have somewhat figured out a way to compare two files. But for some reason it is not giving me the

问题 I am trying to implement a custom binary search to run over a vector of dates. My binary search function is the following: template <typename RandomAccessIterator, typename Value, typename Comparer> inline int binary_search(RandomAccessIterator const first, RandomAccessIterator const last, Value const& value, Comparer comparer) { RandomAccessIterator it(std::lower_bound(first, last, value, comparer)); if (it == last || comparer(*it, value) || comparer(value, *it)) return distance(first,last);