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How to detect reliably Mac OS X, iOS, Linux, Windows in C preprocessor? [duplicate]
If there's some cross-platform C/C++ code that should be compiled on Mac OS X, iOS, Linux, Windows, how can I detect them reliably during preprocessor process?
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Checking if a string can be converted to float in Python
... ------------
print(isfloat("")) False
print(isfloat("1234567")) True
print(isfloat("NaN")) True nan is also float
print(isfloat("NaNananana BATMAN")) False
print(isfloat("123.456")) True
print(isfloat("123.E4")) ...
What is the difference between os.path.basename() and os.path.dirname()?
What is the difference between os.path.basename() and os.path.dirname() ?
2 Answers
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What does the “yield” keyword do?
...one, etc. And generators return... well that's where yield comes in:
def f123():
yield 1
yield 2
yield 3
for item in f123():
print item
Instead of yield statements, if you had three return statements in f123() only the first would get executed, and the function would exit. But f1...
Dynamic SQL - EXEC(@SQL) versus EXEC SP_EXECUTESQL(@SQL)
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EXEC('SELECT * FROM FOO WHERE ID=?', 123) will replace the parameter placeholder "?" with the value 123 and then execute the query, returning a result for SELECT * FROM FOO WHERE ID=123
– Peter Wone
Jun 1 '10 at 23:27
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sed: print only matching group
...it with a 2nd grep.
# To extract \1 from /xx([0-9]+)yy/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'xx[0-9]+yy' | grep -Eo '[0-9]+'
123
4
# To extract \1 from /a([0-9]+)b/
$ echo "aa678bb xx123yy xx4yy aa42 aa9bb" | grep -Eo 'a[0-9]+b' | grep -Eo '[0-9]+'
678
9
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Retrieving Android API version programmatically
...on, the SDK level (integer) the phone is running is available in:
android.os.Build.VERSION.SDK_INT
The class corresponding to this int is in the android.os.Build.VERSION_CODES class.
Code example:
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP){
// Do some...
Correct way to write line to file?
...le:
the_file.write('Hello\n')
From The Documentation:
Do not use os.linesep as a line terminator when writing files opened in text mode (the default); use a single '\n' instead, on all platforms.
Some useful reading:
The with statement
open()
'a' is for append, or use
'w' to write wi...
How do I change the working directory in Python?
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You can change the working directory with:
import os
os.chdir(path)
There are two best practices to follow when using this method:
Catch the exception (WindowsError, OSError) on invalid path. If the exception is thrown, do not perform any recursive operations, especial...
Deleting folders in python recursively
...o. As asked, the question was how to delete EMPTY directories.The docs for os.walk give an example that almost exactly matches this question: import os for root, dirs, files in os.walk(top, topdown=False): for name in dirs: os.rmdir(os.path.join(root, name))
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