variables

问题 This question already has an answer here : Reference template variable within Jinja expression (1 answer) Closed 3 years ago . What is the right way to write something like this in jinja2 : {% for items in zipped %} <img src="{{ url_for('static', filename='img/{{items.logo}}') }}" /> Notice that items.logo is within another variable . 回答1: items.logo is already a variable. Try: {% for items in zipped %} <img src="{{ url_for('static', filename='img/' + items.logo) }}" /> {% endfor %} 来源： https

问题 So lets say I have a class called Car as below: class Car(object): """Car example with weight and speed.""" def __init__(self): self.weight = None self.speed = None If I initialize a Car as an empty object: red_car = Car() And I add a speed and a weight : red_car.speed = 60 red_car.weight = 3500 That's all fine but what if I want to run a function when attempting to add those variables to the instance? Like this function: def change_weight(self, any_int): return (any_int - 10) The thing is

问题 So lets say I have a class called Car as below: class Car(object): """Car example with weight and speed.""" def __init__(self): self.weight = None self.speed = None If I initialize a Car as an empty object: red_car = Car() And I add a speed and a weight : red_car.speed = 60 red_car.weight = 3500 That's all fine but what if I want to run a function when attempting to add those variables to the instance? Like this function: def change_weight(self, any_int): return (any_int - 10) The thing is

问题 I can successfully generate a google map with the code below: var myLatlng = new google.maps.LatLng(37.77493, -122.419415); var myOptions = { zoom: 15, center: myLatlng, mapTypeId: google.maps.MapTypeId.ROADMAP } var map = new google.maps.Map(document.getElementById("map_canvas"), myOptions); However when I try to do it with the block of code below (storing the coordinate in a variable). The map comes up as all blue, with or with out the replace function. var coordinate = "37.77493,-122

问题 How would you appropriately explain why these two examples differ? // Reassignment let a = 1; let b = a; a = 2; console.log(b); // → 1 // Mutation let myArray = [1, 2, 3]; let ourArray = myArray; ourArray[2] = 10; console.log(myArray); // → [1, 2, 10] In regards to why the variable label behaves differently between the two, many resources claim that it's because of the difference between reference types and value types. But, doesn't that only apply to the differences between the values

问题 This question already has answers here : How to exit a SET /p in a batch file (4 answers) Closed 2 years ago . So this is my script/program ; @echo off cls color 0a :startup REM Determinant to Sign (+-*/) set /a deto1=%random% %%4 +1 set /a deto2=%random% %%4 +1 set /a deto3=%random% %%4 +1 set /a deto4=%random% %%4 +1 REM Set Sign from det if %deto1%==1 set o1=+ if %deto1%==2 set o1=- if %deto1%==3 set o1=* if %deto1%==4 set o1=/ if %deto2%==1 set o2=+ if %deto2%==2 set o2=- if %deto2%==3

问题 I am working on a script to get max lengths of each column, I'm trying to store lengths of max length in _c1...n vars. number of columns unknown. I was able to get length for each column, create variables to store each with set _c!i! = !n!, n is the length but in order to set the max length for a particular column I need to compare current with max and use something like !_c!!i!! which doesn't work, any ideas how to refer a variable which part of it's name coming from another variable? Thanks

问题 In C language, scope of the static variable through out the file. In the following code, function returns the static variable. int fun(){ static int i = 10; return i; } int main() { printf("%d\n", fun()); return 0; } And printed output 10. So, Is returning local static in C undefined behaviour or well-defined? 回答1: You seem to have missed the whole logic for a return statement. In this snippet, you are actually returning the value (of the variable), so, without the static storage also, the

问题 I don't know how to use variables when creating Instances or adressing them in Swift: For exmaple how do I do following in a loop (creating Instances): class Guest { let name: String var age: Int init(name: String, age: Int) { self.name = name self.age = age } } let guests = [["ann", 1] , ["bob", 2] ...] so that the loop equals : let ann = Guest(name: "ann" , age: 1) let bob = Guest(name: "bob" , age: 2) ... edit: I am looking for something like this: for i in guests { let i[0] = Guest(name:

问题 In the spirit of seeing Short-circuit evaluation like Python's "and" while storing results of checks I decided to see how this could be best solved in PHP but I've run into an issue. unexpected <?php function check_a() { return 'A'; } function check_b() { return 'B'; } function check_c() { return 'C'; } if($a = check_a() && $b = check_b() && $c = check_c()) { var_dump($a); var_dump($b); var_dump($c); } Results in: bool(true) bool(true) string(1) "C" code for what I wanted to happen <?php