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How to use the PI constant in C++
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On some (especially older) platforms (see the comments below) you might need to
#define _USE_MATH_DEFINES
and then include the necessary header file:
#include <math.h>
and the value of pi can be accessed via:
M_PI
In my math....
What's the difference between a file descriptor and file pointer?
...ther Unix-like systems.
You pass "naked" file descriptors to actual Unix calls, such as read(), write() and so on.
A FILE pointer is a C standard library-level construct, used to represent a file. The FILE wraps the file descriptor, and adds buffering and other features to make I/O easier.
You pa...
CROSS JOIN vs INNER JOIN in SQL
... but not vs CROSS JOIN. Intersection rows are in JOIN, left/right rows are extra (null-extended) rows in LEFT/RIGHT JOIN. It includes CROSS JOIN as a special case of (INNER) JOIN where there are no rows in the non-intersection.
– philipxy
Nov 29 '15 at 0:39
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UIPanGestureRecognizer - Only vertical or horizontal
I have a view that has a UIPanGestureRecognizer to drag the view vertically. So in the recognizer callback, I only update the y-coordinate to move it. The superview of this view, has a UIPanGestureRecognizer that will drag the view horizontally, just updating the x-coordinate.
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How do I create a self-signed certificate for code signing on Windows?
...User\My
2) set the password for it:
$CertPassword = ConvertTo-SecureString
-String "my_passowrd" -Force –AsPlainText
3) Export it:
Export-PfxCertificate -Cert "cert:\CurrentUser\My\$($cert.Thumbprint)"
-FilePath "d:\selfsigncert.pfx" -Password $CertPassword
Your certificate s...
Debugging in Clojure? [closed]
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There's also dotrace, which allows you to look at the inputs and outputs of selected functions.
(use 'clojure.contrib.trace)
(defn fib[n] (if (< n 2) n (+ (fib (- n 1)) (fib (- n 2)))))
(dotrace [fib] (fib 3))
produces the output:
TRACE t4425: (f...
Is there a typical state machine implementation pattern?
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Really nice touch how NUM_STATES is defined.
– Albin Stigo
Dec 19 '15 at 19:38
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std::enable_if to conditionally compile a member function
... I want to use std::enable_if to choose between two member-functions and allow only one of them to be used.
7 Answers
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How do I create a basic UIButton programmatically?
... })];
//set button title for state
[button setTitle:({
NSString* string = [NSString stringWithFormat:@"title words"];
string;
}) forState:({
UIControlState state = UIControlStateNormal;
state;
})];
//set selector
[button addTarget:self action...
How do I get the type of a variable?
...s make it too hard, for example! who says its good to write cout << "String"
– Waqas Tahir
Aug 4 '15 at 16:17
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