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What is the difference between declarative and imperative programming? [closed]
...want.
A simple example in Python:
# Declarative
small_nums = [x for x in range(20) if x < 5]
# Imperative
small_nums = []
for i in range(20):
if i < 5:
small_nums.append(i)
The first example is declarative because we do not specify any "implementation details" of building the ...
How to use sed to remove the last n lines of a file
...he shell do the math, with the goal being to use the d command by giving a range (to remove the last 23 lines):
sed -i "$(($(wc -l < file)-22)),\$d" file
To remove the last 3 lines, from inside out:
$(wc -l < file)
Gives the number of lines of the file: say 2196
We want to remove the la...
Apache: client denied by server configuration
...ons. Different servers though - AWS Linux and Ubuntu 14.10 respectively. Strange... I guess I need to compare each server's httpd.conf files to see if there is a config difference there...
– Darragh Enright
Jul 23 '14 at 1:22
...
Remove all whitespaces from NSString
...ptions:NSRegularExpressionSearch
range:NSMakeRange(0, [myStringlength])];
//myNewString will be @"thisisatest"
You can make yourself a category on NSString to make life even easier:
- (NSString *) removeAllWhitespace
{
return [self stringByReplacin...
B-Tree vs Hash Table
...than with a tree algorithm (O(1) instead of log(n)), but you cannot select ranges (everything in between x and y).
Tree algorithms support this in Log(n) whereas hash indexes can result in a full table scan O(n).
Also the constant overhead of hash indexes is usually bigger (which is no factor in the...
What's the difference between ASCII and Unicode?
...s all world wide alphabets. Hence the size of char in java is 2 bytes. And range is 0 to 65535.
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Random strings in Python
...= string.ascii_lowercase
return ''.join(random.choice(letters) for i in range(length))
Results:
>>> randomword(10)
'vxnxikmhdc'
>>> randomword(10)
'ytqhdohksy'
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impro...
Best ways to teach a beginner to program? [closed]
...ERATION TO SIMPLIFY SQUARE CODE
>>> clear()
>>> for i in range(4):
forward(50)
right(90)
>>>
>>> #INTRODUCE PROCEDURES
>>> def square(length):
down()
for i in range(4):
forward(length)
right(90)
&...
Fast way of counting non-zero bits in positive integer
...You can generate it at runtime:
counts = bytes(bin(x).count("1") for x in range(256)) # py2: use bytearray
Or just define it literally:
counts = (b'\x00\x01\x01\x02\x01\x02\x02\x03\x01\x02\x02\x03\x02\x03\x03\x04'
b'\x01\x02\x02\x03\x02\x03\x03\x04\x02\x03\x03\x04\x03\x04\x04\x05'
...
How to perform element-wise multiplication of two lists?
...ment in a loop. The short hand for doing that is
ab = [a[i]*b[i] for i in range(len(a))]
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