大约有 40,000 项符合查询结果（耗时：0.0706秒） [XML]
Extracting numbers from vectors of strings
...ion is an indirect way of getting to the solution. If you want to retrieve all the numbers, I recommend gregexpr:
matches <- regmatches(years, gregexpr("[[:digit:]]+", years))
as.numeric(unlist(matches))
If you have multiple matches in a string, this will get all of them. If you're only intere...
What is the $? (dollar question mark) variable in shell scripting? [duplicate]
...al Parameters" http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_05_02 :
? Expands to the decimal exit status of the most recent pipeline (see Pipelines).
man bash "Special Parameters":
The shell treats several parameters specially. These parameters may only be refe...
How to call Android contacts list?
I'm making an Android app, and need to call the phone's contact list. I need to call the contacts list function, pick a contact, then return to my app with the contact's name. Here's the code I got on the internet, but it doesnt work.
...
Ruby: Easiest Way to Filter Hash Keys?
...with just the choices in it.
choices = params.select { |key, value| key.to_s.match(/^choice\d+/) }
or you can use delete_if and modify the existing Hash e.g.
params.delete_if { |key, value| !key.to_s.match(/choice\d+/) }
or if it is just the keys and not the values you want then you can do:
p...
What is the difference between log4net and ELMAH?
...,error) with log4net but store it in ELMAH nuget.org/packages/elmahappender_log4net_1.2.10
– Sturla
Feb 18 '14 at 16:21
add a comment
|
...
How do I declare a 2d array in C++ using new?
...
A dynamic 2D array is basically an array of pointers to arrays. You can initialize it using a loop, like this:
int** a = new int*[rowCount];
for(int i = 0; i < rowCount; ++i)
a[i] = new int[colCount];
The above, for colCount= 5 and rowCount =...
When to use static classes in C# [duplicate]
...lity either before or after the old method, we can create a new class and call the old one inside of it - but that's just gross.
Interface woes
Static methods cannot be defined through interfaces for logic reasons. And since we can't override static methods, static classes are useless when we need...
Getting time elapsed in Objective-C
...er to use Apple's function CACurrentMediaTime!
I also benchmarked the mach_timebase_info call and it takes approximately 19ns on my iPhone 6, so I removed the (not threadsafe) code which was caching the output of that call.
#include <mach/mach.h>
#include <mach/mach_time.h>
uint64_t g...
PHP parse/syntax errors; and how to solve them
...as T_STRING explains which symbol the parser/tokenizer couldn't process finally. This isn't necessarily the cause of the syntax mistake, however.
It's important to look into previous code lines as well. Often syntax errors are just mishaps that happened earlier. The error line number is just where ...
How do I replace a git submodule with another repo?
...
answered May 6 '15 at 17:32
hobberwickeyhobberwickey
4,78111 gold badge2222 silver badges2828 bronze badges
...