arrays

How to search in array of object in mongodb

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The right way is: db.users.find({awards: {$elemMatch: {award:’National Medal’, year:1975}}}) $elemMatch allows you to match more than one component within the same array element. Without $elemMatch mongo will look for users with National Medal in some year and some award in the year 1975, but not for users with National Medal in 1975. See MongoDB $elemMatch … Read more

Are arrays in PHP copied as value or as reference to new variables, and when passed to functions?

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For the second part of your question, see the array page of the manual, which states (quoting) : Array assignment always involves value copying. Use the reference operator to copy an array by reference. And the given example : <?php $arr1 = array(2, 3); $arr2 = $arr1; $arr2[] = 4; // $arr2 is changed, // … Read more

Initialization of all elements of an array to one default value in C++?

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Using the syntax that you used, int array[100] = {-1}; says “set the first element to -1 and the rest to 0” since all omitted elements are set to 0. In C++, to set them all to -1, you can use something like std::fill_n (from <algorithm>): std::fill_n(array, 100, -1); In portable C, you have to … Read more

Javascript swap array elements

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You only need one temporary variable. var b = list[y]; list[y] = list[x]; list[x] = b; Edit hijacking top answer 10 years later with a lot of ES6 adoption under our belts: Given the array arr = [1,2,3,4], you can swap values in one line now like so: [arr[0], arr[1]] = [arr[1], arr[0]]; This would … Read more

How to sort an array of objects by multiple fields?

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You could use a chained sorting approach by taking the delta of values until it reaches a value not equal to zero. var data = [{ h_id: “3”, city: “Dallas”, state: “TX”, zip: “75201”, price: “162500” }, { h_id: “4”, city: “Bevery Hills”, state: “CA”, zip: “90210”, price: “319250” }, { h_id: “6”, city: “Dallas”, … Read more