% is for `int` or `long`, not `float` or `double`.

You can use `fmod()` or `fmodf()` from `&lt;math.h&gt;` instead.

Better is [`&lt;tgmath.h&gt;`][1] as [suggested by the inventor of CGFloat][2].


  [1]: http://en.wikipedia.org/wiki/Tgmath.h
  [2]: https://web.archive.org/web/20150806150437/http://www.cocoabuilder.com/archive/cocoa/239717-cgfloat-fmax-fmaxf.html#239897

If I remember correctly modulo requires 2 ints as its input so you&#39;d need something like:

    CGFloat moduloResult = (float)((int)valueB % (int)valueA);

Assuming that valueB and valueA are both floats

Say I have a simple table that has the following fields:

 1. ID: int, autoincremental (identity), primary key
 2. Name: varchar(50), unique, has unique index
 3. Tag: int

I never use the ID field for lookup, because my application is always based on working with the Name field. 

I need to change the Tag value from time to time. I&#39;m using the following trivial SQL code: 

    UPDATE Table SET Tag = XX WHERE Name = YY;

I wondered if anyone knows whether the above is always faster than:

    DELETE FROM Table WHERE Name = YY;
    INSERT INTO Table (Name, Tag) VALUES (YY, XX);

Again - I know that in the second example the ID is changed, but it does not matter for my application.



In SQL, is UPDATE always faster than DELETE+INSERT?

I&#39;m receiving a dict from one &quot;layer&quot; of code upon which some calculations/modifications are performed before passing it onto another &quot;layer&quot;. The original dict&#39;s keys &amp; &quot;string&quot; values are `unicode`, but the layer they&#39;re being passed onto only accepts `str`.

This is going to be called often, so I&#39;d like to know what would be the fastest way to convert something like:

    { u&#39;spam&#39;: u&#39;eggs&#39;, u&#39;foo&#39;: True, u&#39;bar&#39;: { u&#39;baz&#39;: 97 } }

...to:

    { &#39;spam&#39;: &#39;eggs&#39;, &#39;foo&#39;: True, &#39;bar&#39;: { &#39;baz&#39;: 97 } }

...bearing in mind the non-&quot;string&quot; values need to stay as their original type.

Any thoughts?

Fastest way to convert a dict&#39;s keys &amp; values from `unicode` to `str`?

I have two CGFloat values, and want to calculate the modulo result. Or in other words: I want to know what&#39;s left if valueA is placed as much as possible into valueB.

So I just tried:

    CGFloat moduloResult = valueB % valueA;

the compiler complains about the % and tells me: &quot;invalid operands to binary %&quot;. Any idea?

How to make a modulo operation in objective-c / cocoa touch?

I have two CGFloat values, and want to calculate the modulo result. Or in other words: I want to know what's left if valueA is placed as much as possible into valueB.
So I just tried:
<pre><code class="hljs language-ini">CGFloat moduloResult = valueB % valueA;
</code></pre>
the compiler complains about the % and tells me: "invalid operands to binary %". Any idea?

Is it possible to add a shadow to the text in a `UITextField`?

Drop Shadow on UITextField text

I have one crash in my iPhone application that does throw an NSException. The crash reports are completely ambiguous in where the error is and what exactly is causing it. Is there a smart way for me to set a top level exception handler somewhere to see what is causing it? I can&#39;t replicate the problem myself, but a few of my beta users certainly can.

What&#39;s a smart way to handle a problem of this nature?

How do you implement global iPhone Exception Handling?

What setDateFormat option for NSDateFormatter do I use to get a month-day&#39;s ordinal suffix?

e.g. the snippet below currently produces:&lt;br&gt;
3:11 PM Saturday August 15

What must I change to get:&lt;br&gt;
3:11 PM Saturday August 15**th**

    NSDate *date = [NSDate date];
    NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
    [dateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
    [dateFormatter setDateFormat:@&quot;h:mm a EEEE MMMM d&quot;];
    NSString *dateString = [dateFormatter stringFromDate:date];	
    NSLog(@&quot;%@&quot;, dateString);

In PHP, I&#39;d use this for the case above:&lt;br&gt;
`&lt;?php echo date(&#39;h:m A l F jS&#39;) ?&gt;`

Is there an NSDateFormatter equivalent to the **S** option in the PHP formatting string?

Ordinal Month-day Suffix Option for NSDateFormatter setDateFormat

I am getting a strange error message from the core data when trying to save
but the problem that the error is not reproducible ( it appears at different times when doing different tasks)

**the error message:**

    Unresolved error Domain=NSCocoaErrorDomain Code=1560 UserInfo=0x14f5480 &quot;Operation could not be completed. (Cocoa error 1560.)&quot;, {
    NSDetailedErrors = (
    Error Domain=NSCocoaErrorDomain Code=1570 UserInfo=0x5406d70 &quot;Operation could not be completed. (Cocoa error 1570.)&quot;,
    Error Domain=NSCocoaErrorDomain Code=1570 UserInfo=0x14f9be0 &quot;Operation could not be completed. (Cocoa error 1570.)&quot;
    );
    }


and the method that generates the error is:

    - (IBAction)saveAction:(id)sender {
        NSError *error;
        if (![[self managedObjectContext] save:&amp;error]) {
    		// Handle error
    		NSLog(@&quot;Unresolved error %@, %@, %@&quot;, error, [error userInfo],[error localizedDescription]);
    		exit(-1);  // Fail
        }
    }

any idea for the reason of this message ? giving that it appears at random times 

iphone Core Data Unresolved error while saving

What&#39;s the difference between NSNumber and NSInteger? Are there more primitives like these that I should know about? Is there one for floats?

What&#39;s the difference between NSNumber and NSInteger?

I&#39;m embarrassed to ask such a simple question. My term does not start for two more weeks so I can&#39;t ask a professor, and the suspense would kill me.

Why does 2 mod 4 = 2?


Why does 2 mod 4 = 2?

I&#39;m messing with the modulo operation in python and I understand that it will spit back what the remainder is.

But what if the first number is smaller than the second?

for instance

2 % 5  the answer is 2.

How does that work?

2/5 = .4





How does a modulo operation work when the first number is smaller?

I have found that the same mod operation produces different results depending on what language is being used.

In Python:

    -1 % 10

produces **9**

In C it produces **-1** !

1. Which one is the right modulo? &lt;br&gt;
2. How to make mod operation in C to be the same like in Python?

C and Python - different behaviour of the modulo (%) operation

How to calculate modulus of 5^55 modulus 221 without much use of calculator?

I guess there are some simple principles in number theory in cryptography to calculate such things.

How to calculate modulus of large numbers?

I have a 128-bit unsigned integer A and a 64-bit unsigned integer B. What&#39;s the fastest way to calculate `A % B` - that is the (64-bit) remainder from dividing A by B?

I&#39;m looking to do this in either C or assembly language, but I need to target the 32-bit x86 platform. This unfortunately means that I cannot take advantage of compiler support for 128-bit integers, nor of the x64 architecture&#39;s ability to perform the required operation in a single instruction.

**Edit:**

Thank you for the answers so far. However, it appears to me that the suggested algorithms would be quite slow - wouldn&#39;t the fastest way to perform a 128-bit by 64-bit division be to leverage the processor&#39;s native support for 64-bit by 32-bit division? Does anyone know if there is a way to perform the larger division in terms of a few smaller divisions?

**Re: How often does B change?**

Primarily I&#39;m interested in a general solution - what calculation would you perform if A and B are likely to be different every time?

However, a second possible situation is that B does not vary as often as A - there may be as many as 200 As to divide by each B. How would your answer differ in this case?

Content Type	Original Author	Original Content on Stackoverflow
Question	HelloMoon	View Question on Stackoverflow
Solution 1 - Iphone	mouviciel	View Answer on Stackoverflow
Solution 2 - Iphone	James	View Answer on Stackoverflow

How to make a modulo operation in objective-c / cocoa touch?

Iphone Problem Overview

Iphone Solutions

Solution 1 - Iphone

Solution 2 - Iphone

Fastest way to convert a dict's keys & values from `unicode` to `str`?

In SQL, is UPDATE always faster than DELETE+INSERT?

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