i have two variable string both have same time like a= 4:15 PM and b = 4:15 PM
i am trying to compare these two variables in if to perform a specific task but it always returns false
is there any solution?
It would be easier to help if you provided some of the code you are having problems with. If you are absolutely certain both strings have the same exact sequence of characters it should be as simple as comparing them with a == b. You could try using breakpoints in xcode to check the state of the variables before they are compared.
Related
If I have a set of boolean variables in Pascal, how can I test if exactly one of them is True?
In Pascal you can do this:
if Integer(a) + Integer(b) + Integer(c) = Integer(true) then
writeln("exactly one is true");
It's important to compare to Integer(true), since it could be different values in different versions of Pascal.
When looking at Matlab code I have stumbled upon the following line of code:
[~,ui] = Unique(Day)
(Where Day is the vector containing a numeric value of day like so: 1,2,3, etc.)
What is it doing? I have noticed that it creates some kind of unique identifiers for the numeric value of the day (i.e. for 1 to 31) as well as a variable called Volume. What is Volume?
[~,ui] = Unique(Day) evaluates the function Unique with input argument Day.
This function has 2 outputs, and if you want to use both, you would write
[a,b]=Unique(Day). However, if you need only second output, you can put ~ instead of the first argument. So, your first output will not be saved.
It is impossible to answer, what Volume means, because you didn't provide the code of the function Unique.
I have variables with incremented numbers within, such as row0text, row1text, row2text, etc.
I've figured out how to dynamically create string versions of those variable names, but once I have those strings, how can I use them as actual variable names rather than strings in my code?
Example:
var row3text = "This is the value I need!"
var firstPart = "row"
var rowNumber = 3
var secondPart = "text"
var together = (firstPart+String(rowNumber)+secondPart)
// the below gives me the concatenated string of the three variables, but I'm looking for a way to have it return the value set at the top.
println (together)
Once I know how to do this, I'll be able to iterate through those variables using a for loop; it's just that at the moment I'm unsure of how to use that string as a variable name in my code.
Thanks!
Short Answer: There is no way to do this for good reason. Use arrays instead.
Long Answer:
Essentially you are looking for a way to define an unknown number of variables that are all linked together by their common format. You are looking to define an ordered set of elements of variable length. Why not just use an array?
Arrays are containers that allow you to store an ordered set or list of elements and access them by their ordered location, which is exactly what you're trying to do. See Apple's Swift Array Tutorial for further reading.
The advantage of arrays is that they are faster, far more convenient for larger sets of elements (and probably the same for smaller sets as well), and they come packaged with a ton of useful functionality. If you haven't worked with arrays before it is a bit of a learning curve but absolutely worth it.
How to simplify a given boolean expression with many variables (>10) so that the number of occurrences of each variable is minimized?
In my scenario, the value of a variable has to be considered ephemeral, that is, has to recomputed for each access (while still being static of course). I therefor need to minimize the number of times a variable has to be evaluated before trying to solve the function.
Consider the function
f(A,B,C,D,E,F) = (ABC)+(ABCD)+(ABEF)
Recursively using the distributive and absorption law one comes up with
f'(A,B,C,E,F) = AB(C+(EF))
I'm now wondering if there is an algorithm or method to solve this task in minimal runtime.
Using only Quine-McCluskey in the example above gives
f'(A,B,C,E,F) = (ABEF) + (ABC)
which is not optimal for my case. Is it save to assume that simplifying with QM first and then use algebra like above to reduce further is optimal?
I usually use Wolfram Alpha for this sort of thing.
Try Logic Friday 1
It features multi-level design of boolean circuits.
For your example, input and output look as follows:
You can use an online boolean expression calculator like https://www.dcode.fr/boolean-expressions-calculator
You can refer to Any good boolean expression simplifiers out there? it will definitely help.
I am new to coding and objective C so thanks for the help in advance.
I have a .plist file containing an array of strings filled with formulas such as
*5.3
/2
-10.5
I am able to retrieve these string values from the .plist file but I am getting a little stuck trying to append these string formulas to existing variables with the hopes of returning a converted number. For example I would like to use my variable 7 with the formula *5.3 and return 37.1
7 *5.3 -> 37.1
Any help would be greatly appreciated
Appending the string to a variable is straightforward; it can be accomplished with something like this:
NSString *equation = [NSString stringWithFormat:#"%d%#", variable, plistEntry];
You'll run into problems when you want to evaluate this equation, however. This SO question discusses expression evaluation in Objective-C. Dave DeLong's answer links to a couple of libraries that you may want to look into: DDMathParser and GCMathParser.
This can't be done as-is. You'll need one of the many free expression evaluators (probably in C) that float around on the web.
See this SO question.