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Method call if not null in C#
...ke();
or:
obj?.SomeMethod();
The ?. is the null-propagating operator, and will cause the .Invoke() to be short-circuited when the operand is null. The operand is only accessed once, so there is no risk of the "value changes between check and invoke" problem.
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Prior to C# 6, no: there is no...
Difference between two lists
...Using Except is exactly the right way to go. If your type overrides Equals and GetHashCode, or you're only interested in reference type equality (i.e. two references are only "equal" if they refer to the exact same object), you can just use:
var list3 = list1.Except(list2).ToList();
If you need t...
Cloning a MySQL database on the same MySql instance
...s a bit dodgy.
Integrated from various good other answers
Both mysqldump and mysql commands accept options for setting connection details (and much more), like:
mysqldump -u <user name> --password=<pwd> <original db> | mysql -u <user name> -p <new db>
Also, if the ...
jQuery Data vs Attr?
What is the difference in usage between $.data and $.attr when using data-someAttribute ?
3 Answers
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printf() formatting for hex
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The # part gives you a 0x in the output string. The 0 and the x count against your "8" characters listed in the 08 part. You need to ask for 10 characters if you want it to be the same.
int i = 7;
printf("%#010x\n", i); // gives 0x00000007
printf("0x%08x\n", i); // gives 0x0...
Find rows that have the same value on a column in MySQL
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This query will give you a list of email addresses and how many times they're used, with the most used addresses first.
SELECT email,
count(*) AS c
FROM TABLE
GROUP BY email
HAVING c > 1
ORDER BY c DESC
If you want the full rows:
select * from table where email ...
AngularJS disable partial caching on dev machine
... browser cache - In Chrome Dev Tools on the bottom right click on the gear and tick the option
Disable cache (while DevTools is open)
Update: In Firefox there is the same option in Debugger -> Settings -> Advanced Section (checked for Version 33)
Update 2: Although this option appears ...
Hover and Active only when not disabled
I use hover , active and disabled to style Buttons.
7 Answers
7
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How can we redirect a Java program console output to multiple files?
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Go to run as and choose Run Configurations -> Common and in the Standard Input and Output you can choose a File also.
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What does the @ symbol represent in objective-c?
I'm learning objective-c and keep bumping into the @ symbol. It is used in different scenarios, for example at the start of a string or to synthesise accessor methods.
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