What Does the Double Percentage Sign (%%) Mean

What does the double percentage sign (%%) mean?

The "Arithmetic operators" help page (which you can get to via ?"%%") says

‘%%’ indicates ‘x mod y’

which is only helpful if you've done enough programming to know that this is referring to the modulo operation, i.e. integer-divide x by y and return the remainder. This is useful in many, many, many applications. For example (from @GavinSimpson in comments), %% is useful if you are running a loop and want to print some kind of progress indicator to the screen every nth iteration (e.g. use if (i %% 10 == 0) { #do something} to do something every 10th iteration).

Since %% also works for floating-point numbers in R, I've just dug up an example where if (any(wts %% 1 != 0)) is used to test where any of the wts values are non-integer.

What does a double percentage sign (%%) mean in JavaScript?

It appears to be a templating tool, that the people who made the template would change according to what they want to put in there.

Significance of double percent signs (%%) in T-SQL PATINDEX

The official documentation of PATINDEX states that:

pattern
Is a character expression that contains the sequence to be found. Wildcard characters can be used; however, the % character must come before and follow pattern (except when you search for first or last characters)

The % wildcard stands for,
as written in the official documentation for LIKE:

any string of zero or more characters.

The fact that it can stand for any number of characters including zero, means that %% is completely equivalent to % and there for can be safely be changed.

Please note that this is not the case with any other T-SQL wildcards - since _ stands for a single char, as well as [] and [^].

What does the double percent symbol do in Python?

This is not Python-specific. Whoever wrote that code is using the string "%%NOM%% as a placeholder, and using it to substitute the value of nom.

What's the difference between % and %% for comments?

From a syntax point of view, they are both comments.

In the Matlab editor, Matlab parses %% delimited blocks as "sections" which you can run as a unit independent of running the whole script.

What does a double-percent sign (%%) do in gcc inline assembly?

GCC inline assembly uses %0, %1, %2, etc. to refer to input and output operands. That means you need to use two %% for real registers.

Check this howto for great information.

In R, how does double percent work when used on a matrix?

(Hope I haven't over explained this and interpreted what you're asking correctly:)

As you've said, you know that %% is the modulus operator. So

a <- data.frame(1:50)
a %% 10

returns 'x mod 10' for each item in the frame (or 1,2,3,4,5,6,7,8,9,0 etc etc)

The two examples you've given are like 'shorthand' for if statements. In pseudo code:

for n = 1 to length of a
    if a[n] %% 10 equals zero 
      return true
    else 
      return false

So a %% 10 == 0 is "Does the element mod 10 equal zero" and a %% 10 == 2 is "Does the element mod 10 equal two" applied to each element

And the result is matrix of logicals (booleans).

Double percent sign in css

The width:50%% is invalid, it means <audio> will take the user agent style i.e. width:300px (See in the inspect) in chrome. Thats why its working.

The width:50% is valid, but in your case width is not working because your parent has 0 width and 0% of 0 is also 0.

Try to give width in px or give width to your parent.

Stack Snippet

<div class="col-md-8" style="display:inline-block;">  <audio style="width:100px" controls="controls">    Your browser does not support the <code>audio</code> element.    <source src="music_mix.mp3" type="audio/mp3">   </audio></div>

What do the %op% operators in mean? For example %in% ?

Put quotes around it to find the help page. Either of these work

> help("%in%")
> ?"%in%"

Once you get to the help page, you'll see that

‘%in%’ is currently defined as

‘"%in%" <- function(x, table) match(x, table, nomatch = 0) > 0’

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Since time is a generic, I don't know what time(X2) returns without knowing what X2 is. But, %in% tells you which items from the left hand side are also in the right hand side.

> c(1:5) %in% c(3:8)
[1] FALSE FALSE  TRUE  TRUE  TRUE

See also, intersect

> intersect(c(1:5), c(3:8))
[1] 3 4 5

mysql LIKE with double percent

As in the answer Mihir Dave's comment links to, there's no difference to SQL if you pass %% instead of %. Since a single % matches zero or more characters, then each of the metacharacters in %% would also match zero or more, and ultimately the same string would match one way or another.

But I'd guess your legacy code is pre-Python 2.6 that uses % as a metacharacter in string formatting, and you have to double it like %% to get a single literal % character.

See also:

• How can I selectively escape percent (%) in Python strings?
• https://docs.python.org/2.6/library/stdtypes.html#string-formatting-operations

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