string-concatenation

问题 I have the variable: $myvar = 'myarchive.pdf'; How can I embedd it to this: echo('<tr> <td> <a href="nextpage.php?file=trial.pdf"> download now </a> </td> </tr>'); I wonder if there is a way to do it like this: echo('<tr> <td> <a href="nextpage.php?file=".'$myvar'.> download now </a> </td> </tr>'); 回答1: You are not appending the variable to the string properly. Also you have to enclose nextpage.php?file=variable within quotes. But you are closing it before the variable name. <a href="nextpage

问题 I have the variable: $myvar = 'myarchive.pdf'; How can I embedd it to this: echo('<tr> <td> <a href="nextpage.php?file=trial.pdf"> download now </a> </td> </tr>'); I wonder if there is a way to do it like this: echo('<tr> <td> <a href="nextpage.php?file=".'$myvar'.> download now </a> </td> </tr>'); 回答1: You are not appending the variable to the string properly. Also you have to enclose nextpage.php?file=variable within quotes. But you are closing it before the variable name. <a href="nextpage

问题 How can I concatenate: A = {'hello'; 'hi'; 'hey'} with B = {'Ben'; 'Karen'; 'Lisa'} with a space in between to get: C = {'hello Ben'; 'hi Karen'; 'hey Lisa'} Is there a fast non-looping way? 回答1: You can use strcat() , although it performs a loop: strcat(A,{' '}, B) where the blank is preserved by enclosing it within a cell. Alternatively, FEX:CStrCatStr is a mex routine which achieves a 10x speedup (depending on testing environment): CStrCatStr(A,' ', B) 回答2: A faster (albeit less elegant)

问题 I am working with spark 2.2.0 and pyspark2. I have created a DataFrame df and now trying to add a new column "rowhash" that is the sha2 hash of specific columns in the DataFrame. For example, say that df has the columns: (column1, column2, ..., column10) I require sha2((column2||column3||column4||...... column8), 256) in a new column "rowhash" . For now, I tried using below methods: 1) Used hash() function but since it gives an integer output it is of not much use 2) Tried using sha2()

问题 I would like to concatenate a variable with a string. In line 7 to line 11 I try to concat !somevariable! with a string or with %%P variable. But this does not seem to work. I.e. you have file 0_1_en.pdf in current folder. The script shortcuts the name of file to first digit. Afterwards I want to create a new variable with a string for example: "GEN 0" where 0 is the !sPDFName! Complete code: 1 SETLOCAL EnableDelayedExpansion 2 for /f "delims=" %%P in ('dir /b *.pdf') do ( 3 SET "sPDFName=%%

问题 On every site that talks about VBScript, the ' & ' operator is listed as the string concatenation operator. However, in some code that I have recently inherited, I see the ' + ' operator being used and I am not seeing any errors as a result of this. Is this an accepted alternative? 回答1: The + operator is overloaded, whereas the & operator is not. The & operator only does string concatenation. In some circles the & operator is used as a best practice because it is unambiguous, and therefore

问题 My question is this: Is string concatenation in C# safe? If string concatenation leads to unexpected errors, and replacing that string concatenation by using StringBuilder causes those errors to disappear, what might that indicate? Background: I am developing a small command line C# application. It takes command line arguments, performs a slightly complicated SQL query, and outputs about 1300 rows of data into a formatted XML file. My initial program would always run fine in debug mode.

问题 This question already has answers here : How does the String class override the + operator? (7 answers) Closed 6 years ago . I saw this question a few minutes ago, and decided to take a look in the java String class to check if there was some overloading for the + operator. I couldn't find anything, but I know I can do this String ab = "ab"; String cd = "cd"; String both = ab + cd; //both = "abcd" Where's that implemented? 回答1: From the Fine Manual: The Java language provides special support

问题 This question already has answers here : How does the String class override the + operator? (7 answers) Closed 6 years ago . I saw this question a few minutes ago, and decided to take a look in the java String class to check if there was some overloading for the + operator. I couldn't find anything, but I know I can do this String ab = "ab"; String cd = "cd"; String both = ab + cd; //both = "abcd" Where's that implemented? 回答1: From the Fine Manual: The Java language provides special support

问题 I have a array that looks like this: $array = [ ["444", "0081"], ["449", "0081"], ["451", "0081"], ["455", "2100"], ["469", "2100"] ]; I need to group as a new array that looks like: array ( 0 => array ( 0 => '444,449,451', 1 => '0081', ), 1 => array ( 0 => '455,469', 1 => '2100', ), ) I'd tried many scripts, but with no success. function _group_by($array, $key) { $return = array(); foreach($array as $val) { $return[$val[$key]][] = $val; } return $return; } $newArray = _group_by($array, 1); /