default-value

Python argparse: default value or specified value

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import argparse parser = argparse.ArgumentParser() parser.add_argument(‘–example’, nargs=”?”, const=1, type=int) args = parser.parse_args() print(args) % test.py Namespace(example=None) % test.py –example Namespace(example=1) % test.py –example 2 Namespace(example=2) nargs=”?” means 0-or-1 arguments const=1 sets the default when there are 0 arguments type=int converts the argument to int If you want test.py to set example to 1 even if … Read more

Change default text in input type=”file”?

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Use the for attribute of label for input. <div> <label for=”files” class=”btn”>Select Image</label> <input id=”files” style=”visibility:hidden;” type=”file”> </div> Below is the code to fetch name of the uploaded file $(“#files”).change(function() { filename = this.files[0].name; console.log(filename); }); <script src=”https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js”></script> <div> <label for=”files” class=”btn”>Select Image</label> <input id=”files” style=”visibility:hidden;” type=”file”> </div>

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

Named tuple and default values for optional keyword arguments

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Python 3.7 Use the defaults parameter. >>> from collections import namedtuple >>> fields = (‘val’, ‘left’, ‘right’) >>> Node = namedtuple(‘Node’, fields, defaults=(None,) * len(fields)) >>> Node() Node(val=None, left=None, right=None) Or better yet, use the new dataclasses library, which is much nicer than namedtuple. >>> from dataclasses import dataclass >>> from typing import Any >>> … Read more