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How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
...ns:
- Range.
E.g. a-z matches an lower case letters from a to z
E.g. 0-5 matches any number from 0 to 5
[] Match exactly one of the objects inside these brackets.
E.g. [a] matches the letter a
E.g. [abc] matches a single letter which can be a, b or c
E.g. [a-z] matches any single lower cas...
Is “argv[0] = name-of-executable” an accepted standard or just a common convention?
When passing argument to main() in a C or C++ application, will argv[0] always be the name of the executable? Or is this just a common convention and not guaranteed to be true 100% of the time?
...
What's the simplest way to test whether a number is a power of 2 in C++?
...
190
(n & (n - 1)) == 0 is best. However, note that it will incorrectly return true for n=0, so i...
Are members of a C++ struct initialized to 0 by default?
... constructors
struct Snapshot {
int x;
double y;
Snapshot():x(0),y(0) { }
// other ctors / functions...
};
Will initialize both x and y to 0. Note that you can use x(), y() to initialize them disregarding of their type: That's then value initialization, and usually yields a proper...
How to remove leading zeros from alphanumeric text?
...s leading zeroes, but leaves one if necessary (i.e. it wouldn't just turn "0" to a blank string).
s.replaceFirst("^0+(?!$)", "")
The ^ anchor will make sure that the 0+ being matched is at the beginning of the input. The (?!$) negative lookahead ensures that not the entire string will be matched....
How to split a string and assign it to variables
...ort (
"fmt"
"strings"
)
func main() {
s := strings.Split("127.0.0.1:5432", ":")
ip, port := s[0], s[1]
fmt.Println(ip, port)
}
Output:
127.0.0.1 5432
One step, for example,
package main
import (
"fmt"
"net"
)
func main() {
host, port, err := net.SplitHostPort...
Removing leading zeroes from a field in a SQL statement
...ve the leading zeroes from a particular field, which is a simple VARCHAR(10) field. So, for example, if the field contains '00001A', the SELECT statement needs to return the data as '1A'.
...
Dynamically select data frame columns using $ and a character value
...itten as
`$`(df , V1)
or indeed
`$`(df , "V1")
But...
`$`(df , paste0("V1") )
...for instance will never work, nor will anything else that must first be evaluated in the second argument. You may only pass a string which is never evaluated.
Instead use [ (or [[ if you want to extract only...
Finding sum of elements in Swift array
...d.
Swift 3 and Swift 4:
let multiples = [...]
let sum = multiples.reduce(0, +)
print("Sum of Array is : ", sum)
Swift 2:
let multiples = [...]
sum = multiples.reduce(0, combine: +)
Some more info:
This uses Array's reduce method (documentation here), which allows you to "reduce a collectio...
How do I convert a numpy array to (and display) an image?
...
240
You could use PIL to create (and display) an image:
from PIL import Image
import numpy as np
w...