Changing position of two items.
Act of rearranging the locations of two items such that the first item now occupies the place of the second and the second item now occupies the place of the first.
Questions tagged [swap]
2503 questions
73
votes
2 answers
Is id = 1 - id atomic?
From page 291 of OCP Java SE 6 Programmer Practice Exams, question 25:
public class Stone implements Runnable {
static int id = 1;
public void run() {
id = 1 - id;
if (id == 0)
pick();
else
…
Adam Stelmaszczyk
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58
votes
2 answers
std::swap vs std::exchange vs swap operator
An implementation of std::swap might look like this:
template void swap (T& a, T& b)
{
T c(std::move(a)); a=std::move(b); b=std::move(c);
}
template void swap (T (&a)[N], T (&b)[N])
{
for (size_t i = 0; i
user1508519
58
votes
6 answers
iter_swap() versus swap() -- what's the difference?
MSDN says:
swap should be used in preference to iter_swap, which was included in the C++ Standard for backward compatibility.
But comp.std.c++ says:
Most STL algorithms operate on iterator ranges. It therefore makes sense to
use iter_swap when…
user541686
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57
votes
10 answers
Why is a = (a+b) - (b=a) a bad choice for swapping two integers?
I stumbled into this code for swapping two integers without using a temporary variable or the use of bitwise operators.
int main(){
int a=2,b=3;
printf("a=%d,b=%d",a,b);
a=(a+b)-(b=a);
printf("\na=%d,b=%d",a,b);
return 0;
}
But…
ashfaque
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56
votes
1 answer
Swapping elements in an NSMutableArray
Are there any special methods to make swapping elements in an NSMutableArray easier or more direct?
node ninja
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56
votes
19 answers
How to write a basic swap function in Java
I am new to java. How to write the java equivalent of the following C code.
void Swap(int *p, int *q)
{
int temp;
temp = *p;
*p = *q;
*q = temp;
}
Melinda
- 577
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54
votes
13 answers
Is it possible to write swap method in Java?
Here is the question: write a method that swaps two variables. These two variables should be primitives. It doesn't need to be generic e.g. two int variables. Is there a way?!
Khaled Alshaya
- 94,250
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50
votes
8 answers
Java method to swap primitives
how do I make my swap function in java if there is no method by which we can pass by reference? Could somebody give me a code?
swap(int a, int b)
{
int temp = a;
a = b;
b = temp;
}
But the changes wont be reflected back since java…
higherDefender
- 1,551
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47
votes
7 answers
Can I tell Linux not to swap out a particular processes' memory?
Is there a way to tell Linux that it shouldn't swap out a particular processes' memory to disk?
Its a Java app, so ideally I'm hoping for a way to do this from the command line.
I'm aware that you can set the global swappiness to 0, but is this…
sanity
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46
votes
1 answer
Swap two rows in a numpy array in python
How to swap xth and yth rows of the 2-D NumPy array? x & y are inputs provided by the user.
Lets say x = 0 & y =2 , and the input array is as below:
a = [[4 3 1]
[5 7 0]
[9 9 3]
[8 2 4]]
Expected Output :
[[9 9 3]
…
Manish
- 649
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46
votes
3 answers
How do I swap tensor's axes in TensorFlow?
I have a tensor of shape (30, 116, 10), and I want to swap the first two dimensions, so that I have a tensor of shape (116, 30, 10)
I saw that numpy as such a function implemented (np.swapaxes) and I searched for something similar in tensorflow but…
Alexis Rosuel
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44
votes
6 answers
Why are there so many specializations of std::swap?
While looking at the documentation for std::swap, I see a lot of specializations.
It looks like every STL container, as well as many other std facilities have a specialized swap.
I thought with the aid of templates, we wouldn't need all of these…
Trevor Hickey
- 36,288
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43
votes
3 answers
Linker performance related to swap space?
Sometimes it's handy to mock up something with a little C program that uses a big chunk of static memory. I noticed after changing to Fedora 15 the program took a long time to
compile. We're talking 30s vs. 0.1s. Even more weird was that ld…
Rooke
- 2,013
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41
votes
8 answers
Add swap memory with ansible
I'm working on a project where having swap memory on my servers is a needed to avoid some python long running processes to go out of memory and realized for the first time that my ubuntu vagrant boxes and AWS ubuntu instances didn't already have one…
gonz
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41
votes
2 answers
Is std::swap(x, x) guaranteed to leave x unchanged?
This question is based on discussion below a recent blog post by Scott Meyers.
It seems "obvious" that std::swap(x, x) should leave x unchanged in both C++98 and C++11, but I can't find any guarantee to that effect in either standard. C++98 defines…
KnowItAllWannabe
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