In dynamically typed language, truthiness is a term used to describe a value that might evaluate to boolean true.
Questions tagged [truthiness]
99 questions
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In which languages is a string not always truthy?
Are there any (other) programming languages where string 'false' is not a truthy value?
php yes:
echo "" | php
yes
python kind of:
>>> print(('false'==True))
False
>>> print(bool('false'))
True
>>>
javascript:…
111
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1 answer
VueJS - How to check the truthiness of an object of objects for a v-if
I have this appointments object that has three keyed arrays. I'm trying to find a clean JS way to check the truthiness for a v-if when all three block arrays are empty a la:
{
"block_1": [],
"block_2": [],
"block_3": []
}
I have…
Matt Larsuma
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4 answers
Why can we cast bool to str?
We know how bool() acts on various python objects such as str, int, list.
This is a question about the reverse.
You can cast bool to int as
>>> int(True)
1
>>> int(False)
0
which I think kinda makes sense, but with string we get
>>>…
joel
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2 answers
Callback function with a truthy value in JavaScript
This is my very first post on StackOverflow, and I would be grateful if you could help me clarify, at a conceptual level, what's happening in the following JavaScript function. So, I've been practicing the language for a while, and I'm now diving a…
Bruno Mazza
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2 answers
Assertions and testing emptiness of iterables
Using the built-in assert statement, is there a good, Pythonic way of checking emptiness in an iterable? I have seen:
One-liner to check whether an iterator yields at least one element?;
Is there any way to check with Python unittest assert if an…
blacksite
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1 answer
Python script to count pixel values fails on a less-than/greater-than comparison
I wrote a short script to count the pixel values in an image:
import os
import sys
import cv2
import numpy as np
imn = (sys.argv[1])
a = cv2.imread(imn, 0)
b = cv2.imread(imn, 1)
c = cv2.GaussianBlur(cv2.imread(imn, 0), (7,7), 2)
def NC(img):
…
Rich
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1 answer
Stuck on JavaScript koans "about_truthyness" section
I'm working on Koans by liammclennan and I'm stuck on the "about_truthyness" section with the following code:
module("About Truthyness (topics/about_truthyness.js)");
test("truthyness of positive numbers", function() {
var oneIsTruthy = 1 ?…
Bartek
- 1
0
votes
1 answer
Truthiness checker function in JavaScript
I am going through this challenge on FCC and I am literally half way there!
Check if the predicate (second argument) is truthy on all elements of
a collection (first argument).
function truthCheck(collection, pre) {
// Is everyone being…
Antonio Pavicevac-Ortiz
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2 answers
Groovy null check not working on a property in the list
POJO:
class Item{
String prop1
String prop2
}
My Data:
List- items = new ArrayList(new Item(prop1: 'something'), new Item(prop1: 'something'))
Then I try:
if(items?.prop2){
//I thought prop 2 is present
}
even though…
user2069929
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0
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0 answers
Why would a truthy check on an enum value not work like I expect?
On my membership model, I have the following enum value:
enum relative_type: { member: 0, user: 1 }
Then elsewhere in some code, when it comes upon a membership model, I have this if-branch
if membership.user?
member =…
marcamillion
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4 answers
In javascript is -1 true or false?
I can't figure out if -1 is true or false in javascript, when I use indexOf.
let a = 'abc'.indexOf('abc');
let b = 'def'.indexOf('abc');
console.log(a); // 0
console.log(b); // -1
console.log(!a); // true
console.log(!b); //…
roro
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1 answer
Why call bool() directly?
I've read that when python evaluates a conditional, that something like if x: would be translated to if bool(x):. Why then do I see a lot of code that calls bool() directly? Is this mostly for readability or is there some other advantage?
Jpaji Rajnish
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votes
7 answers
Do-while loop not observing truth assignment (C)
My C project is a Windows console app that takes the time signature and BPM from a user's musical project and returns the length of a bar in seconds.
I am trying to use a do-while loop to add a "continue/exit?" prompt at the end of each successful…
Nathaniel Lindsey
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0
votes
1 answer
Iterate collection for truthy/falsey values
I have some outstanding requirements for a school assignment that should return truthy/falsy values from a collection. Here are the outstanding requirements:
1) Should pass for a collection of all truthy results
2) Should pass for a collection…
user4774635
0
votes
1 answer
How to check "truthyness" of an object, and then delete the falsy ones and edit the object
I need to take this object, check each properties truthyness, and then remove the untruthy ones.
var user = {
name: 'my name',
email: null,
pwHash: 'U+Ldlngx2BYQk',
birthday: undefined,
username: 'myname33',
age: 0
}
Here is the code I was trying…
Dylan Lott
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