conditional-statements

问题 I am going through this code. I would like to know what is meant by -le in the following code segment. if [ $stage -le 2 ]; then In one of the questions it says that -le stands for <= of strings, but that is in Perl. Is it the same here as well? Further, I would like to know if that $stage variable automatically gets updated. It has been initialized to 0 at the beginning, but later, how does that get incremented? 回答1: -le checks if the value of left operand is less than or equal to ( <= ) the

问题 I have a set of data in the following format: Resp | Q1 | Q2 P1 | 4 | 5 P2 | 1 | 2 P3 | 4 | 3 P4 | 6 | 4 I'd like to show the count and % of people who gave an answer greater than 3. So in this case, the output would be: Question | Count | Percent Q1 | 3 | 75% Q2 | 2 | 50% Any suggestions? 回答1: Although it sounds like a fairly easy thing, it is a bit more complicated. Firstly your data is not row based so you will have to pivot it. Load your data into Tableau In the DataSource Screen choose

问题 How are multiple range queries implemented in CouchDB? For a single range condition, startkey and endkey combination works fine, but the same thing is not working with a multiple range condition. My View function is like this: "function(doc){ if ((doc['couchrest-type'] == 'Item') && doc['loan_name']&& doc['loan_period']&& doc['loan_amount']) { emit([doc['template_id'], doc['loan_name'],doc['loan_period'], doc['loan_amount']],null);}}" I need to get the whole docs with loan_period > 5 and loan

问题 How can I evaluate the constants C1 and C2 from a solution of a differential equation SymPy gives me? There are the initial condition f(0)=0 and f(pi/2)=3. >>> from sympy import * >>> f = Function('f') >>> x = Symbol('x') >>> dsolve(f(x).diff(x,2)+f(x),f(x)) f(x) == C1*sin(x) + C2*cos(x) I tried some ics stuff but it's not working. Example: >>> dsolve(f(x).diff(x,2)+f(x),f(x), ics={f(0):0, f(pi/2):3}) f(x) == C1*sin(x) + C2*cos(x) By the way: C2 = 0 and C1 = 3. 回答1: There's a pull request

问题 I need to update newly created column in my oracle table. To do so I need to use existing values in row to decide how to populate this column, I am getting error: java.lang.NullPointerException -> See Debug Output for details This is my query: UPDATE SCHEMA_NAME.TABLE_NAME SET OCO= IF CO= 'Y' AND COM='Y' THEN { 'Y' } ELSE { 'N' } END IF; Any suggestions on syntax? 回答1: You could use CASE expression in the SET clause. For example, UPDATE table SET schema.column = CASE WHEN CO= 'Y' AND COM='Y'

问题 This question already has answers here : IF IE conditionals not working (5 answers) Closed 5 years ago . I am using IE 11 version. Is there any other solution to do the following: Nothing happens when I try to use conditional IE clause in the html webapge. Can anyone help me debug this issue please. <!--[if IE]> <a href="next-page.php" class="start-button">CLICK ME</a> <![endif]--> 回答1: Conditional statements do not work in IE 10 or 11 Support for conditional comments has been removed in

问题 I need a particular script to be triggered in Internet Explorer browsers Only! I've tried this: <!--[if IE]> <script></script> <![endif]--> Unfortunately this actually stops the script from being loaded. EDIT: For everyone asking why I need this: IE makes scrolling extremely jumpy when using some animations. In order to address this I need to implement a script that provides smooth scrolling to IE. I don't want to apply it to other browsers as they don't need it and this script although

问题 Just wondering if anyone has come across this before. I found in a project (that was handed over from another developer) a conditional statement that looked something like this: if (variableOne == true | variable2 == true) { // Do something here } It didn't error, so seems to work. But, myself and a colleague have never seen an OR statement with a single pipe | , only 2 || . Can anyone shed light on this mystery? Thanks, James 回答1: This is a bitwise OR operator. It will first convert it into

问题 I have recently started using Zend Studio which has reported as warning the following type of code: $q = query("select * from some_table where some_condition"); while ($f = fetch($q)) { // some inner workings } To stop the warning the code needs to be written like this: $q = query("select * from some_table where some_condition"); $f = fetch($q); while ($f) { // some inner workings $f = fetch($q); } Why is this marked as a warning? Is it so bad? I understand that the warning may be designed to

问题 In C or C++ if ( x ) statement1; else statement2; For what value of x will both statements be executed? I know we can execute if-else together like this: if(1){ goto ELSE; } else{ ELSE: } Is there any way, like a value? (Which I think is not possible. Asking because someone is arguing!) 回答1: for what value of x both statements will be executed? There is no such value: either the value evaluates to true (something != 0), or it evaluates to false ) (0). No other possible values exist. I know we