I`m truing to create graph of function in Qt 5 Qcustomplot. But I can fix this problem.
I use next code for get set x y
for (X = xBegin; X <= xEnd; X+=h)
{
double y_ptr = start_processing(ptr_string.data(), X);
if(y_ptr > ui->doubleSpinBox_3->value() && y_ptr < ui->doubleSpinBox_4->value())
{
x.push_back(X);
y.push_back(y_ptr);
}
}
Related
I had to swap 2 numbers in one line expression using no other variable except x and y.
So I wrote the following .c program to swapp two numbers with the given conditions and it works like charm.
int main() {
int x =5, y =2;
x = y-x+(y=x);
printf("X=%d, y=%d", x, y);
return 0;
}
But when i try to do the same in kotlin it gives me an error that
Assignments are not expressions, and only expressions are allowed in
this context,
I can resolve this issue by introducing a third variable just like this. But I'm not allowed to have any other variable except x and y which are already given. So is there any other way I can do this in one line using any kotlin property?
Below is the kotlin program
fun main() {
var x = 5
var y = 10
x = y-x+(y=x)
println("X = $x, Y = $y")
}
While I have two suggestions below, I want to start with a recommendation against either of them, at least in this simple example.
It's usually a lot more clear to optimise code for developers to read in the following ways:
create an extra variable with a descriptive name
prefer val over var to avoid accidental mutations
and try to make the code 'linear', so the operations can be read from top-to-bottom without jumping between functions
avoid code that needs an IDE to see what the type-hints are
And I'll trust that the compiler will make make the code performant.
fun main() {
val x = 5
val y = 10
val newX = y
val newY = x
println("X = $newX, Y = $newY")
}
Local function
You could use a local function to perform the swap, as the function will still be able to access the original values.
fun main() {
var x = 5
var y = 10
fun swap(originalX: Int, originalY: Int) {
y = originalX
x = originalY
}
swap(x, y)
println("X = $x, Y = $y")
}
Scope function
This could be code-golfed into one line
use to to create a Pair<Int, Int>,
and a scope function to use the result.
fun main() {
var x = 5
var y = 10
(x to y).apply { x = second; y = first }
println("X = $x, Y = $y")
}
One line? Yes. More difficult to read? I think so.
So I tried to write a code that finds the largest palindromic number from two (3 spaces long) multiplied numbers. Does my code work fine or are there no palindromes for this?
function checkPalindrom(str) {
return str === str.split('').reverse().join('');
}; //Declares the funciton to check if a string is a palindrome
var x = 999;
var y = 999;
var z = 0;
var n = z.toString(); //Declares that n is the string of z
for (i=0; i<899; i++) { //For loop: counts from 0 to 899
x*y===z; //Is this correct? z is set equal to x*y
if(checkPalindrom(n) === true) { //If n is a palindrome,
console.log(n); //Write out the palindrome
} else {
x-=1; //subtract 1 from x and run again
}
};
Also, what is the best way to check for all combinations of 3 digit numbers? Because right now I am just checking for any number from 100 to 999, but I actually need to check for all combinations...
Your post has a few problems, as well as multiple questions in it. I'll try to hone in on the major stuff but, as this is a fairly standard type of Programming 101 homework question, I'm not going to give you an exact answer right out.
First off, there are three different 'equals' in javascript, =, ==, and ===. A single = is an assignment operator and it always works from right to left. Thus,
var x = 2;
assigns the value of 2 to the variable x. In your code,
x*y === z;
has a couple of problems. First off, it is backwards. Secondly, it uses === but should be using =.
z = x*y;
That is what you were trying to put here.
In javascript, == and === are both comparitives. The triple === adds type comparison and is stronger but generally unnecessary. In almost all cases, == is sufficient. But, what it does is compare the values like inside an if statement:
if(x == 2)
This just checks if the value of x is equal to the value of 2, but the values themselves do not change.
Ok, for your other question: "number from 100 to 999, but I actually need to check for all combinations..."
The best way to handle this is a double loop:
var z;
for(var x = 100; x < 1000; x++)
for(var y = x; y < 1000; y++)
z = x*y;
This will first let x = 100, then check 100 * every number from 100 to 999. Then you let x = 101 and check 101* every number from 101 to 999.
function checkPalindrom(str) {
return str === str.split('').reverse().join('');
}; //Declares the funciton to check if a string is a palindrome
var x;
var y;
var z;
var n;
var max = 0;
for (x=999; x >= 100; x--) {
for (y=999; y >= 100; y--) {
z = x*y;
n = z.toString();
if(checkPalindrom(n) === true && max < z) {
console.log(n);
max = z;
}
}
}
Hi so I am trying to create an if statement where...if the sprite has been touched...then something will happen
However, for some reason, I am getting an expected identified error and can't for the life of me figure out why?
Thank you for any help and knowledge you can provide meKKInput* input = [KKInput sharedInput];
KKInput* input = [KKInput sharedInput];
if([input isAnyTouchOnNode:kan touchPhase:[KKTouchPhaseAny]])
{
for ( int x = 105.0f; x < 100000 ; ++x)
{
for ( int y = 50.0f; y < 100000 ; ++y)
{
kan.position = CGPointMake((x),(y));
}
}
}
The square brackets around KKTouchPhaseAny (probably an enum) must be removed.
I tried using 6%2, but its always giving the value as 2 and not 0. Why and how can I get a solution to this?
if(!(y%x))
{
...
}
In your case !(6%2) would return true.
(Answer very similar to the original in the question)
I'm asuming that you want to find out if Y=kX has integer values of k for a given X so that Y=5, X=3 fails (k is 5/3), but Y=6, X=2 passes (k is exactly 3). You are happy that k is either positive or negative.
That way, using Y remainder X == 0 is a good test. As an aside, be careful of negative remainders (e.g. Y % 2 == 1 as a test for oddness fails for negative numbers, use Y % 2 != 0 to be sure)
Code example in Java
public class Example {
public static void main(String[] args) {
System.out.println(isIntegerFactor(5,3)); // k is not an integer
System.out.println(isIntegerFactor(6,3)); // k is 2
System.out.println(isIntegerFactor(-6,-3)); // k is 2
System.out.println(isIntegerFactor(-6,3)); // k is -2
System.out.println(isIntegerFactor(6,-3)); // k is -2
}
public static boolean isIntegerFactor(int y, int x) {
return (y % x) == 0;
}
}
bool prime = PrimeTool.IsPrime(input_Number);
if (!prime)
{
Console.Write("multiple of other number");
Console.WriteLine(i);
}
i'm making a simple iPhone game using cocos2d-iphone. I have an array of fiends, the "fiendSet" which has to navigate around a field full of obstacles. I spent the last three nights trying to get my A* pathfinding to work. I found the actual A* implementation here on stackoverflow and it works brilliantly. However, once i try to move my fiends around i run into trouble.
Each of my fiends has a CGPoint called motionTarget which contains the x and y values for where the fiend has to go. If only set the positions x and y to absolute values once a second, it works, like so:
-(void) updateFiendPositions:(ccTime)dt {
for (MSWFiend *currFiend in fiendSet) {
currFiend.position = ccp(currFiend.motionTarget.x,currFiend.motionTarget.y);
}
}
However, this doesn't look very nice, the fiends just "jump" 20px each second instead of animating nicely. I only implemented this as a placeholder method to verify the pathfinding. Now i want smooth animation. This is what i did:
-(void) updatePositions:(ccTime) dt {
for (MSWFiend *currFiend in fiendSet) {
if (currFiend.motionTarget.x != -1 && currFiend.motionTarget.y != -1) {
float x,y;
if ((int)floor(currFiend.position.x) < (int)floor(currFiend.motionTarget.x)) {
x = currFiend.position.x+(currFiend.speed*dt);
}
if ((int)floor(currFiend.position.x) > (int)floor(currFiend.motionTarget.x)) {
x = currFiend.position.x-(currFiend.speed*dt);
}
if (abs((int)floor(currFiend.position.x)-(int)floor(currFiend.motionTarget.x)) < 2) {
x = currFiend.motionTarget.x;
}
if ((int)floor(currFiend.position.y) < (int)floor(currFiend.motionTarget.y)) {
y = currFiend.position.y+(currFiend.speed*dt);
}
if ((int)floor(currFiend.position.y) > (int)floor(currFiend.motionTarget.y)) {
y = currFiend.position.y-(currFiend.speed*dt);
}
if (abs((int)floor(currFiend.position.y)-(int)floor(currFiend.motionTarget.y)) < 2) {
y = currFiend.motionTarget.y;
}
currFiend.position = ccp(x,y);
}
}
}
This works great for fiends moving in one direction. As soon as a fiend is supposed to go around a bend, trouble starts. Instead of for example first going up, then right, then down; my fiends will combine the up/right motion into one, they are "cutting corners". I only want my fiends to move either north/south OR east/west for each position update, not both. In other words, i don't want to animate changes to x and y simultaneously. I hope this explanation is clear enough..
I'm pretty sure i have a logic error somewhere.. i just havn't been able to figure it out for the last three sleepless nights after work.. Help!
You have to keep track of each node in the path to the target. That way you only animate the motion to the next node. Also you can use a CCMoveTo action instead on doing the animation yourself.
#Aleph thanks for your suggestion. I found that it was the code which determines when to assign a new motionTarget, that was faulty, not the code i posted to begin with. When you mentioned keeping track of each nodes position, i thought of my motionTarget determination code and found the error after 2-3 hours. I ended up doing it like this:
-(void) updatePositions:(ccTime) dt {
for (MSWFiend *currFiend in fiendSet) {
int fiendGX,fiendGY,targetGX,targetGY,dGX,dGY;
float x,y,snappedX,snappedY;
BOOL snappedIntoPosition = FALSE;
fiendGX = (int)round(100.0f*(currFiend.position.x/20));
fiendGY = (int)round(100.0f*(currFiend.position.y/20));
targetGX = (int)round(100.0f*(currFiend.motionTarget.x/20));
targetGY = (int)round(100.0f*(currFiend.motionTarget.y/20));
snappedX = currFiend.position.x;
snappedY = currFiend.position.y;
dGX = abs(fiendGX-targetGX);
dGY = abs(fiendGY-targetGY);
float snappingThreshold; //1 = snap when 0.1 from motionTarget.
snappingThreshold = currFiend.speed/10;
if (dGX < snappingThreshold && dGY < snappingThreshold) {
snappingThreshold = currFiend.motionTarget.x;
snappingThreshold = currFiend.motionTarget.y;
int newPathStep;
newPathStep = currFiend.pathStep + 1;
currFiend.pathStep = newPathStep;
}
int gX,gY;
gX = [[currFiend.path objectAtIndex:currFiend.pathStep] nodeX];
gY = (tileMap.mapSize.height-[[currFiend.path objectAtIndex:currFiend.pathStep] nodeY])-1;
currFiend.motionTarget = ccp(gX*20,gY*20); //Assign motion target to the next A* node. This is later used by the position updater.
if (currFiend.motionTarget.x != -1 && currFiend.motionTarget.y != -1) {
x = currFiend.motionTarget.x;
y = currFiend.motionTarget.y;
if ((int)floor(currFiend.position.x) < (int)floor(currFiend.motionTarget.x)) {
//Move right
x = snappedX+(currFiend.speed*dt);
if (x > currFiend.motionTarget.x) {
x = currFiend.motionTarget.x;
}
y = snappedY;
}
if ((int)floor(currFiend.position.x) > (int)floor(currFiend.motionTarget.x)) {
//Move left
x = snappedX-(currFiend.speed*dt);
if (x < currFiend.motionTarget.x) {
x = currFiend.motionTarget.x;
}
y = snappedY;
}
if ((int)floor(currFiend.position.y) < (int)floor(currFiend.motionTarget.y)) {
//Move up
y = snappedY+(currFiend.speed*dt);
if (y > currFiend.motionTarget.y) {
y = currFiend.motionTarget.y;
}
x = snappedX;
}
if ((int)floor(currFiend.position.y) > (int)floor(currFiend.motionTarget.y)) {
//Move down
y = snappedY-(currFiend.speed*dt);
if (y < currFiend.motionTarget.y) {
y = currFiend.motionTarget.y;
}
x = snappedX;
}
}
currFiend.position = ccp(x,y);
}
}