A process of setting or re-setting the value stored in the storage location(s) denoted by a variable name.
Questions tagged [variable-assignment]
4336 questions
3837
votes
12 answers
Why don't Java's +=, -=, *=, /= compound assignment operators require casting long to int?
Until today, I thought that for example:
i += j;
Was just a shortcut for:
i = i + j;
But if we try this:
int i = 5;
long j = 8;
Then i = i + j; will not compile but i += j; will compile fine.
Does it mean that in fact i += j; is a shortcut for…
Honza Brabec
- 37,388
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700
votes
5 answers
Command not found error in Bash variable assignment
I have this script called test.sh:
#!/bin/bash
STR = "Hello World"
echo $STR
when I run sh test.sh I get this:
test.sh: line 2: STR: command not found
What am I doing wrong? I look at extremely basic/beginners bash scripting tutorials online and…
Jake Wilson
- 88,616
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508
votes
26 answers
Why does this go into an infinite loop?
I have the following code:
public class Tests {
public static void main(String[] args) throws Exception {
int x = 0;
while(x<3) {
x = x++;
System.out.println(x);
}
}
}
We know he should have…
The Student
- 27,520
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407
votes
12 answers
JavaScript OR (||) variable assignment explanation
Given this snippet of JavaScript...
var a;
var b = null;
var c = undefined;
var d = 4;
var e = 'five';
var f = a || b || c || d || e;
alert(f); // 4
Can someone please explain to me what this technique is called (my best guess is in the title of…
chattsm
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398
votes
9 answers
How can I index a MATLAB array returned by a function without first assigning it to a local variable?
For example, if I want to read the middle value from magic(5), I can do so like this:
M = magic(5);
value = M(3,3);
to get value == 13. I'd like to be able to do something like one of these:
value = magic(5)(3,3);
value = (magic(5))(3,3);
to…
Joe Kearney
- 7,397
- 6
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389
votes
14 answers
Is it possible only to declare a variable without assigning any value in Python?
Is it possible to declare a variable in Python, like so?:
var
so that it initialized to None? It seems like Python allows this, but as soon as you access it, it crashes. Is this possible? If not, why?
EDIT: I want to do this for cases like…
Joan Venge
- 315,713
- 212
- 479
- 689
361
votes
12 answers
Assign output of a program to a variable using a MS batch file
I need to assign the output of a program to a variable using a MS batch file.
So in GNU Bash shell I would use VAR=$(application arg0 arg1). I need a similar behavior in Windows using a batch file.
Something like set VAR=application arg0…
initialZero
- 6,197
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- 38
345
votes
4 answers
Set variable in jinja
I would like to know how can I set a variable with another variable in jinja. I will explain, I have got a submenu and I would like show which link is active. I tried this:
{% set active_link = {{recordtype}} -%}
where recordtype is a variable…
MyTux
- 3,459
- 2
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- 4
337
votes
12 answers
Initialization of all elements of an array to one default value in C++?
C++ Notes: Array Initialization has a nice list over initialization of arrays. I have a
int array[100] = {-1};
expecting it to be full with -1's but its not, only first value is and the rest are 0's mixed with random values.
The code
int array[100]…
Milan
- 15,389
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286
votes
12 answers
What is the difference between shallow copy, deepcopy and normal assignment operation?
import copy
a = "deepak"
b = 1, 2, 3, 4
c = [1, 2, 3, 4]
d = {1: 10, 2: 20, 3: 30}
a1 = copy.copy(a)
b1 = copy.copy(b)
c1 = copy.copy(c)
d1 = copy.copy(d)
print("immutable - id(a)==id(a1)", id(a) == id(a1))
print("immutable - id(b)==id(b1)",…
deeshank
- 4,286
- 4
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270
votes
16 answers
How to assign from a function which returns more than one value?
Still trying to get into the R logic... what is the "best" way to unpack (on LHS) the results from a function returning multiple values?
I can't do this apparently:
R> functionReturningTwoValues <- function() { return(c(1, 2)) }
R>…
mariotomo
- 9,438
- 8
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250
votes
7 answers
What is the difference between i++ and ++i in C#?
I've seen them both being used in numerous pieces of C# code, and I'd like to know when to use i++ and when to use ++i?
(i being a number variable like int, float, double, etc).
Dlaor
- 2,900
- 3
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221
votes
8 answers
Multiple left-hand assignment with JavaScript
var var1 = 1,
var2 = 1,
var3 = 1;
This is equivalent to this:
var var1 = var2 = var3 = 1;
I'm fairly certain this is the order the variables are defined: var3, var2, var1, which would be equivalent to this:
var var3 = 1, var2 = var3, var1…
David Calhoun
- 8,315
- 4
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212
votes
14 answers
Why is x == (x = y) not the same as (x = y) == x?
Consider the following example:
class Quirky {
public static void main(String[] args) {
int x = 1;
int y = 3;
System.out.println(x == (x = y)); // false
x = 1; // reset
System.out.println((x = y) == x);…
John McClane
- 3,498
- 3
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- 33
202
votes
10 answers
R: += (plus equals) and ++ (plus plus) equivalent from c++/c#/java, etc.?
Does R have a concept of += (plus equals) or ++ (plus plus) as c++/c#/others do?
Suraj
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