in my code I have the following if statement:
if (a.count >= 2) {
t2 = array[b % a.count];
array[0] = t2;
}
I have another if statement that goes like the first. What I want it to do is if a <= 0 then goto a certain line, or skip over certain parts of code. How would I do this? I was thinking something along the lines of
if (a.count <= 0) {
goto line 96
}
This wouldn't work, the syntax is wrong, but how would I do this?
Goto statements are generally considered bad programming and excessive utilization of them can lead to code that is hard to maintain and debug.
That said, if/else/else if provide all the functionality you need.
I recommend putting the code you need to run inside that if statement in a separate method and then calling it from the if statement.
if (a.count <= 0) {
nameOfNewMethod();
}
//somewhere else
- (void) nameOfNewMethod {
//code here
}
Put the lines of code you want to "goto" in a function (or if appropriate, a block) and call the function (or block). If there are lines of code you want to skip, you can always return early out of a function, or use an else block?
There is in fact a goto command in Objective-C. To utilize it, you have to create a label, ex:
marker:
and jump to it like so within the same method:
goto marker;
But you can't declare any variables between those two commands. All the variables have to be created before the jump so that they still exist after.
Here's an example of how to use goto:
int x = 0;
if (a.count <= 0) {
goto marker;
}
x = 5;
marker:; // <-- semi-colon indicates the label is followed by an empty statement, thus allowing for immediate variable declaration
int y = x + 7;
In that case, if a.count <= 0, y == 7, else y == 12.
Related
In java I got this construction
for (let i = 0; i < x.length-1; I++
And here to avoid outOfBoundsException we are using x.length-1 but how to do the same thing in Kotlin? I got this code so far
x.forEachIndexed { index, _ ->
output.add((x[index+1]-x[index])*10)
}
And it crashes on the last element when we call x[index+1] so I need to handle the last element somehow
Input list
var x = doubleArrayOf(0.0, 0.23, 0.46, 0.69, 0.92, 1.15, 1.38, 1.61)
For a classic Java for loop you got two options in Kotlin.
One would be something like this.
val x = listOf(1,2,3,4)
for (i in 0 .. x.lastIndex){
// ...
}
Using .. you basically go from 0 up to ( and including) the number coresponding to the second item, in this case the last index of the list.( so from 0 <= i <= x.lastIndex)
The second option is using until
val x = listOf(1,2,3,4)
for (i in 0 until x.size){
// ...
}
This is similar to the previous approach, except the fact that until is not inclusive with the last element.(so from 0 <= i < x.size ).
What you probably need is something like this
val x = listOf(1,2,3,4)
for (i in 0 .. x.lastIndex -1){
// ...
}
or alternative, using until, like this
val x = listOf(1,2,3,4)
for (i in 0 until x.size-1){
// ...
}
This should probably avoid the IndexOut of bounds error, since you go just until the second to last item index.
Feel free to ask more if something is not clear.
This is also a great read if you want to learn more about ranges. https://kotlinlang.org/docs/ranges.html#progression
You already have an answer, but this is another option. If you would use a normal list, you would have access to zipWithNext(), and then you don't need to worry about any index, and you can just do:
list.zipWithNext { current, next ->
output.add((next - current)*10)
}
As mentioned by k314159, we can also do asList() to have direct access to zipWithNext and other list methods, without many drawbacks.
array.asList().zipWithNext { current, next ->
output.add(next - current)
}
I want to make a cave explorer game in game maker 8.0.
I've made a block object and an generator But I'm stuck. Here is my code for the generator
var r;
r = random_range(0, 1);
repeat(room_width/16) {
repeat(room_height/16) {
if (r == 1) {
instance_create(x, y, obj_block)
}
y += 16;
}
x += 16;
}
now i always get a blank frame
You need to use irandom(1) so you get an integer. You also should put it inside the loop so it generates a new value each time.
In the second statement, you are generating a random real value and storing it in r. What you actually require is choosing one of the two values. I recommend that you use the function choose(...) for this. Here goes the corrected statement:
r = choose(0,1); //Choose either 0 or 1 and store it in r
Also, move the above statement to the inner loop. (Because you want to decide whether you want to place a block at the said (x,y) location at every spot, right?)
Also, I recommend that you substitute sprite_width and sprite_height instead of using the value 16 directly, so that any changes you make to the sprite will adjust the resulting layout of the blocks accordingly.
Here is the code with corrections:
var r;
repeat(room_width/sprite_width) {
repeat(room_height/sprite_height) {
r = choose(0, 1);
if (r == 1)
instance_create(x, y, obj_block);
y += sprite_height;
}
x += sprite_width;
}
That should work. I hope that helps!
Looks like you are only creating a instance if r==1. Shouldn't you create a instance every time?
Variable assignment r = random_range(0, 1); is outside the loop. Therefore performed only once before starting the loop.
random_range(0, 1) returns a random real number between 0 and 1 (not integer!). But you have if (r == 1) - the probability of getting 1 is a very small.
as example:
repeat(room_width/16) {
repeat(room_height/16) {
if (irandom(1)) {
instance_create(x, y, obj_block)
}
y += 16;
}
x += 16;
}
Here's a possible, maybe even better solution:
length = room_width/16;
height = room_height/16;
for(xx = 0; xx < length; xx+=1)
{
for(yy = 0; yy < height; yy+=1)
{
if choose(0, 1) = 1 {
instance_create(xx*16, yy*16, obj_block); }
}
}
if you want random caves, you should probably delete random sections of those blocks,
not just single ones.
For bonus points, you could use a seed value for the random cave generation. You can also have a pathway random generation that will have a guaranteed path to the finish with random openings and fake paths that generate randomly from that path. Then you can fill in the extra spaces with other random pieces.
But in regards to your code, you must redefine the random number each time you are placing a block, which is why all of them are the same. It should be called inside of the loops, and should be an integer instead of a decimal value.
Problem is on the first line, you need to put r = something in the for cycle
I am developing an app where the user receives an overall score and are judged from that score and given a title. However, with the code I am using, the end result is always the same, no matter what score the subject gets. I dont know if this a math problem or a code problem, as it always comes up with the first option: You have no SWAG whatsoever...
if (totalScore<24) {
describe.text = #"You have no SWAG whatsoever...";
}
else if (25<totalScore<49) {
describe.text = #"You seem to be new to SWAG.";
}
else if (50<totalScore<74) {
describe.text = #"You have a bit of SWAG, not enough though.";
}
else if (75<totalScore<99) {
describe.text = #"You definately have SWAG!";
}
else if (totalScore == 100) {
describe.text = #"You are a GOD of SWAG.";
}
else if (25<totalScore<49) {
should be:
else if (25<totalScore && totalScore<49) {
The way you wrote it is parsed as if you'd written:
else if ((25<totalScore) < 49) {
25<totalScore will be either 1 or 0 depending on whether it's true or false. Either way, it's less than 49.
Also, all your comparisons should be <= rather than <. Otherwise, you're excluding all the boundary values.
building if in this way
if (25<totalScore<49) {...}
is risky.In reality you do something like
25<totalScore -> YES/NO (values will be casted from BOOL to int as 1/0)
and then you will do
0/1 < 49 which will be always true.
so in total your if is wrong.
Your first line of code looks right from what you have displayed so far? You need to output what total score is. You are maybe not setting it before running your code?
Failing that, are you sure its compiling properly? You need to use && in your subsequent if statements.
Also, you need to use <=, because at the moment, if the score is 24 it wont work.
I'm trying to create a loop than continues to take input until the input gives the command to break the loop. What I'm doing now looks a little like this:
int start = 1;
while (start == 1) {
//Program statement
}
However, I feel as though there is an easier, more effective way to create a loop that repeats until the user gives the command to stop it. Does something like that exist?
A common idiom to express a "forever" loop in C and other C-like languages, including Objective-C, is to use an empty for:
for(;;) {
// statements
}
You should do it like this:
while(true)
{
if( exit_condition)
{
break;
}
}
do{
userInput = readUserInput()
}while(userInput != exit_condition)
Any loop as for, while, or even goto can do this job. If you put a condition instead of "true" in the loop, You can reduce code and doesn't need to use the "break" statement.
I'm a newbie to this site, so if I mess up any question-asking etiquette here I apologize in advance... Thanks!
This is extremely simplified example code, but I think it shows what I'm talking about: I have a C++ method that makes a call into another method to test a value...
char m_array[MAX]; // class member, MAX is a #define
foo(unsigned int n)
{
if (validNumber(n)) //test n
{
// do stuff
m_array[n-1] = 0;
}
}
where: validNumber(unsigned int val) { return ((val > 0) && (val <= MAX)); }
The irritation I'm having is that PC Lint's Value Tracking seems to ignore the validNumber() call and gives a warning 661 possible access of out-of-bounds pointer (1 beyond end of data) by operator '['
However if I do it like this, Lint is happy:
if ((n > 0) && (n <= MAX)) //test n
...
So, does Lint's Value Tracking just not work if the test is a method call?
Thanks again,
HF
I'd guess that validNumber is defined after foo, but in any case, PC Lint normally makes one pass over the code, and in such cases it doesn't see validNumber as a check for the boundaries for n.
You could try the option -passes(2) or even 3, and see what Lint makes out of it. I think (but didn't try) that Lint would then correctly note that the value for n is within the correct bounds.