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Convert array of integers to comma-separated string
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var result = string.Join(",", arr);
This uses the following overload of string.Join:
public static string Join<T>(string separator, IEnumerable<T> values);
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How to replace a hash key with another key
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If all the keys are strings and all of them have the underscore prefix, then you can patch up the hash in place with this:
h.keys.each { |k| h[k[1, k.length - 1]] = h[k]; h.delete(k) }
The k[1, k.length - 1] bit grabs all of k except the firs...
How to append rows to an R data frame
...<- function(n){
df <- data.frame(x = numeric(n), y = character(n), stringsAsFactors = FALSE)
for(i in 1:n){
df$x[i] <- i
df$y[i] <- toString(i)
}
df
}
Here's a similar approach, but one where the data.frame is created as the last step.
# Use preallocated vectors
f4 <...
jQuery Get Selected Option From Dropdown
...ted').text();
or generically:
$('#id :pseudoclass')
This saves you an extra jQuery call, selects everything in one shot, and is more clear (my opinion).
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Getting the name of a variable as a string
This thread discusses how to get the name of a function as a string in Python:
How to get a function name as a string?
23 ...
Realistic usage of the C99 'restrict' keyword?
...ons could be saved, as mentioned by supercat.
Consider for example:
void f(char *restrict p1, char *restrict p2) {
for (int i = 0; i < 50; i++) {
p1[i] = 4;
p2[i] = 9;
}
}
Because of restrict, a smart compiler (or human), could optimize that to:
memset(p1, 4, 50);
memset(...
Why use static_cast(x) instead of (int)x?
...pointer to a different type, and then dereferencing. Except in the case of character types or certain struct types for which C defines the behavior of this construct, it generally results in undefined behavior in C.
– R.. GitHub STOP HELPING ICE
Feb 4 '12 at 5:...
What are the underlying data structures used for Redis?
...u asked, here is the underlying implementation of every Redis data type.
Strings are implemented using a C dynamic string library so that we don't pay (asymptotically speaking) for allocations in append operations. This way we have O(N) appends, for instance, instead of having quadratic behavior.
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What's so bad about Template Haskell?
... lately (using haskell-src-exts / meta) - https://github.com/mgsloan/quasi-extras/tree/master/examples . I know this introduces some bugs such as not being able to splice in the generalized list comprehensions. However, I think that there's a good chance that some of the ideas in http://hackage.hask...
Regex Named Groups in Java
...p "name"
${name} to reference to captured group in Matcher's replacement string
Matcher.group(String name) to return the captured input subsequence by the given "named group".
Other alternatives for pre-Java 7 were:
Google named-regex (see John Hardy's answer)
Gábor Lipták mentions (N...