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What's the opposite of chr() in Ruby?
...comment but add the [0]:
'A'.unpack('C')[0]
The unpack call returns an Array containing a single integer, which is not always accepted where an integer is wanted:
$ ruby -e 'printf("0x%02X\n", "A".unpack("C"))'
-e:1:in `printf': can't convert Array into Integer (TypeError)
from -e:1
$ ruby...
find vs find_by vs where
...hat you supply. Use where (as described below, which will return an empty array if the attribute is not found) to avoid an exception being thrown.
Other uses of find are usually replaced with things like this:
Model.all
Model.first
find_by is used as a helper when you're searching for informati...
Why are we not to throw these exceptions?
...arly, IndexOutOfRangeExceptions occur when you access an invalid index (on arrays—not lists). You should always make sure that you don’t do that in the first place and check the boundaries of e.g. an array first.
There are a few other exceptions like those two, for example InvalidCastException ...
What are C++ functors and their uses?
...u could pass a MultiplyBy object to an algorithm like std::transform:
int array[5] = {1, 2, 3, 4, 5};
std::transform(array, array + 5, array, MultiplyBy(3));
// Now, array is {3, 6, 9, 12, 15}
Another advantage of a functor over a pointer to a function is that the call can be inlined in more case...
How to generate a random number between a and b in Ruby?
...ubyinside.com/ruby-1-9-3-introduction-and-changes-5428.html
Converting to array may be too expensive, and it's unnecessary.
(a..b).to_a.sample
Or
[*a..b].sample
Array#sample
Standard in Ruby 1.8.7+.
Note: was named #choice in 1.8.7 and renamed in later versions.
But anyway, generating a...
Are typedef and #define the same in c?
...int *a, b, c
typedef int a10[10];
a10 a, b, c; // create three 10-int arrays
typedef int (*func_p) (int);
func_p fp; // func_p is a pointer to a function that
// takes an int and returns an int
share
...
Objective-C implicit conversion loses integer precision 'NSUInteger' (aka 'unsigned long') to 'int'
...
The count method of NSArray returns an NSUInteger, and on the 64-bit OS X platform
NSUInteger is defined as unsigned long, and
unsigned long is a 64-bit unsigned integer.
int is a 32-bit integer.
So int is a "smaller" datatype than NSUInteger,...
无社交不商业，Uber将边缘化BAT - 资讯 - 清泛网 - 专注C/C++及内核技术
...辆车，几百万司机，永远是无法撼动的。
当用户习惯使用软件叫车后，又推出了专车服务，专车直接威胁了出租车公司的生存，这下出租车公司才反应过来，想要打击专车服务。但是，这种趋势完全挡不住。
一个月前，我...
Convert RGBA PNG to RGB with PIL
...y as np
FNAME = 'logo.png'
img = Image.open(FNAME).convert('RGBA')
x = np.array(img)
r, g, b, a = np.rollaxis(x, axis = -1)
r[a == 0] = 255
g[a == 0] = 255
b[a == 0] = 255
x = np.dstack([r, g, b, a])
img = Image.fromarray(x, 'RGBA')
img.save('/tmp/out.jpg')
Note that the logo also has some se...
Change default primary key in Eloquent
...composite keys, but here's a good workaround so you can have $primaryKey = array('key1', 'key1'); github.com/laravel/framework/issues/5517#issuecomment-52996610
– mopo922
Jan 27 '15 at 6:36
...