conditional

问题 Sometimes when making conditionals, I need the code to do nothing, e.g., here, I want Bash to do nothing when $a is greater than "10", print "1" if $a is less than "5", otherwise, print "2": if [ "$a" -ge 10 ] then elif [ "$a" -le 5 ] then echo "1" else echo "2" fi This makes an error though. Is there a command which will do nothing and also not slow down my script? 回答1: The no-op command in shell is : (colon). if [ "$a" -ge 10 ] then : elif [ "$a" -le 5 ] then echo "1" else echo "2" fi From

问题 I have two buttons which toggle some additional information on screen. I added the buttons the aria-controls attribute und I render an id for the infobox. Now I still get an error, when I validate the html, because I show this infobox only if a variable in the vuex store is true . I render it with v-if . So that means if the button was not clicked the element is not in the DOM and therefore the corresponding id is missing and I get an error. I tried to use v-show because this would only hide

问题 I have two buttons which toggle some additional information on screen. I added the buttons the aria-controls attribute und I render an id for the infobox. Now I still get an error, when I validate the html, because I show this infobox only if a variable in the vuex store is true . I render it with v-if . So that means if the button was not clicked the element is not in the DOM and therefore the corresponding id is missing and I get an error. I tried to use v-show because this would only hide

问题 I want create a bivariate map plotting two variables: production and possession . In order to give part of the data the correct colour I want to add a column with color codes "A", "B", "C" for one variable and for the other 1, 2, 3 . Then later concatinating the two. Just so that the data is coded like the following example: Here's my example df and failing code: library(dplyr) example_df <- structure(list(production = c(0.74, 1.34, 2.5), possession = c(5, 23.8, 124.89)), .Names = c(

问题 I need to test whether the user is on the account page, but only for the login portion as the title states... Is there a way to do this? 回答1: May be you need to combine ! is_user_logged_in() with is_account_page() , this way: if( ! is_user_logged_in() && is_account_page() ){ // Test something } There is also 2 useful hooks: add_action( 'woocommerce_before_customer_login_form', 'action_woocommerce_before_customer_login_form', 10, 0 ); function testing_login_portion( ) { // Test something }; Or

问题 #include <iostream> using namespace std; int main() { int score; char grade; cout << "Enter your score:" << endl; cin >> score; if (score >= 90) grade = 'a'; if (score >= 80) grade = 'b'; if (score >= 70) grade = 'c'; if (score >= 60) grade = 'd'; else grade = 'f'; cout << grade << endl; switch (grade) { case 'a': cout << "Good job" << endl; break; case 'c': cout << "Fair job" << endl; break; case 'f': cout << "Failure" << endl; break; default: cout << "invalid" << endl; } cin.get(); return 0

问题 #include <iostream> using namespace std; int main() { int score; char grade; cout << "Enter your score:" << endl; cin >> score; if (score >= 90) grade = 'a'; if (score >= 80) grade = 'b'; if (score >= 70) grade = 'c'; if (score >= 60) grade = 'd'; else grade = 'f'; cout << grade << endl; switch (grade) { case 'a': cout << "Good job" << endl; break; case 'c': cout << "Fair job" << endl; break; case 'f': cout << "Failure" << endl; break; default: cout << "invalid" << endl; } cin.get(); return 0

问题 #include <iostream> using namespace std; int main() { int score; char grade; cout << "Enter your score:" << endl; cin >> score; if (score >= 90) grade = 'a'; if (score >= 80) grade = 'b'; if (score >= 70) grade = 'c'; if (score >= 60) grade = 'd'; else grade = 'f'; cout << grade << endl; switch (grade) { case 'a': cout << "Good job" << endl; break; case 'c': cout << "Fair job" << endl; break; case 'f': cout << "Failure" << endl; break; default: cout << "invalid" << endl; } cin.get(); return 0

问题 how should a conditional php include be written for it to take effect? I have edited my cart's main index.php so as to include the appropriate config file based on the current url, though the way it is written doesn't work: (whole file below, my edition is between //mine START and //mine END) <?php session_start(); @$cart = $_SESSION["cart"]; if ($cart == "") { $cart = md5(uniqid(rand())); $_SESSION["cart"] = $cart; } foreach ($_GET as $get_key => $get_value) { if ((preg_match("/\//", $get

问题 how should a conditional php include be written for it to take effect? I have edited my cart's main index.php so as to include the appropriate config file based on the current url, though the way it is written doesn't work: (whole file below, my edition is between //mine START and //mine END) <?php session_start(); @$cart = $_SESSION["cart"]; if ($cart == "") { $cart = md5(uniqid(rand())); $_SESSION["cart"] = $cart; } foreach ($_GET as $get_key => $get_value) { if ((preg_match("/\//", $get