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Convert a character digit to the corresponding integer in C
...sh to check isdigit(c) is true first. Note that you cannot completely portably do the same for letters, for example:
char c = 'b';
int x = c - 'a'; // x is now not necessarily 1
The standard guarantees that the char values for the digits '0' to '9' are contiguous, but makes no guarantees for othe...
Enums and Constants. Which to use when?
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Use enums when you want to define a range of values that something can be. Colour is an obvious example like:
public enum Colour
{
White,
Red,
Blue
}
Or maybe a set of possible things like:
(Example I stole from here as I'm lazy)
[FlagsAttribute]
enum DistributedChannel
{
None ...
Simplest way to detect a mobile device in PHP
What is the simplest way to tell if a user is using a mobile device to browse my site using PHP?
15 Answers
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What do the f and t commands do in Vim?
Can somebody explain to me what the f and t commands do in vim and exactly how they work? I can't seem to find this information but people keep telling me that they are very useful. Would really appreciate an answer with an example if possible, thanks!
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Re-open *scratch* buffer in Emacs?
If I accidentally closed the scratch buffer in Emacs, how do I create a new scratch buffer?
16 Answers
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How to randomize (or permute) a dataframe rowwise and columnwise?
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Given the R data.frame:
> df1
a b c
1 1 1 0
2 1 0 0
3 0 1 0
4 0 0 0
Shuffle row-wise:
> df2 <- df1[sample(nrow(df1)),]
> df2
a b c
3 0 1 0
4 0 0 0
2 1 0 0
1 1 1 0
By default sample() randomly reorders the elements passed as the first argumen...
Is it possible for git-merge to ignore line-ending differences?
Is it possible for git merge to ignore line-ending differences?
10 Answers
10
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What is the difference between square brackets and parentheses in a regex?
...:
/^(7|8|9)\d{9}$/
/^[789]\d{9}$/
/^[7-9]\d{9}$/
The explanation:
(a|b|c) is a regex "OR" and means "a or b or c", although the presence of brackets, necessary for the OR, also captures the digit. To be strictly equivalent, you would code (?:7|8|9) to make it a non capturing group.
[abc] is a...
What are the differences between “=” and “
What are the differences between the assignment operators = and <- in R?
7 Answers
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How to randomly select an item from a list?
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Use random.choice()
import random
foo = ['a', 'b', 'c', 'd', 'e']
print(random.choice(foo))
For cryptographically secure random choices (e.g. for generating a passphrase from a wordlist) use secrets.choice()
import secrets
foo = ['battery', 'correct', 'horse', 'staple...