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Difference between single and double quotes in Bash
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Single quotes won't interpolate anything, but double quotes will. For example: variables, backticks, certain \ escapes, etc.
Example:
$ echo "$(echo "upg")"
upg
$ echo '$(echo "upg")'
$(echo "upg")
The Bash manual has this to say:
3.1.2.2 Single Quotes
Enclosing characters in singl...
Error when testing on iOS simulator: Couldn't register with the bootstrap server
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warning: implicit declaration of function
...for which the compiler has not seen a declaration ("prototype") yet.
For example:
int main()
{
fun(2, "21"); /* The compiler has not seen the declaration. */
return 0;
}
int fun(int x, char *p)
{
/* ... */
}
You need to declare your function before main, like this, either dir...
How can I assign the output of a function to a variable using bash?
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VAR=$(scan)
Exactly the same way as for programs.
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How do I install from a local cache with pip?
... take advantage of this, I've added the following to my ~/.bash_profile:
export PIP_DOWNLOAD_CACHE=$HOME/.pip_download_cache
or, if you are on a Mac:
export PIP_DOWNLOAD_CACHE=$HOME/Library/Caches/pip-downloads
Notes
If a newer version of a package is detected, it will be downloaded and adde...
How to select only the records with the highest date in LINQ
... n by n.AccountId into g
select new {AccountId = g.Key, Date = g.Max(t=>t.Date)};
If you want the whole record:
var q = from n in table
group n by n.AccountId into g
select g.OrderByDescending(t=>t.Date).FirstOrDefault();
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What is Double Brace initialization in Java?
What is Double Brace initialization syntax ( {{ ... }} ) in Java?
13 Answers
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Default value of BOOL
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There is no default value if you write
-(void)somemethod {
BOOL x; // <--- no default value
It is initialized to garbage.
However, for a BOOL ivar, it will be initialized to NO, as the whole instance is filled with 0 on initialization.
(Note: When ARC is enabled, local object poin...
CORS - How do 'preflight' an httprequest?
...o acknowledge these headers in order for the actual request to work.
For example, suppose the browser makes a request with the following headers:
Origin: http://yourdomain.com
Access-Control-Request-Method: POST
Access-Control-Request-Headers: X-Custom-Header
Your server should then respond with...
What is self-documenting code and can it replace well documented code? [closed]
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