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How to remove from a map while iterating it?
...
The standard associative-container erase idiom:
for (auto it = m.cbegin(); it != m.cend() /* not hoisted */; /* no increment */)
{
if (must_delete)
{
m.erase(it++); // or "it = m.erase(it)" since C++11
}
else
{
...
Why does “_” (underscore) match “-” (hyphen)?
... SQL pattern matching enables you to use "_" to match any single character and "%" to match an arbitrary number of characters (including zero characters).
(From section 3.3.4.7. Pattern Matching in the MySQL documentation.)
If you want to use the underscore in like as a literal, you have to escap...
MD5 algorithm in Objective-C
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md5 is available on the iPhone and can be added as an addition for ie NSString and NSData like below.
MyAdditions.h
@interface NSString (MyAdditions)
- (NSString *)md5;
@end
@interface NSData (MyAdditions)
- (NSString*)md5;
@end
MyAdditions.m
#import...
How assignment works with Python list slice?
...lar syntax:
1) slicing:
b = a[0:2]
This makes a copy of the slice of a and assigns it to b.
2) slice assignment:
a[0:2] = b
This replaces the slice of a with the contents of b.
Although the syntax is similar (I imagine by design!), these are two different operations.
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Why are preprocessor macros evil and what are the alternatives?
...d encountered a phrase like "macro should never be used", "macro are evil" and so on, my question is: why? With the new C++11 is there a real alternative after so many years?
...
python exception message capturing
... 2.x
logger.error('Failed to upload to ftp: '+ str(e))
in Python 3.x and modern versions of Python 2.x use except Exception as e instead of except Exception, e:
try:
with open(filepath,'rb') as f:
con.storbinary('STOR '+ filepath, f)
logger.info('File successfully uploaded to ...
Why does Go have a “goto” statement
...nt. I've always been taught that 'goto' statements are a thing of the past and evil for it occludes the actual flow of a program, and that functions or methods are always a better way of controlling flow.
...
Circular list iterator in Python
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(Loops forever, obviously)
In order to manually advance the iterator and pull values from it one by one, simply call next(pool):
>>> next(pool)
'a'
>>> next(pool)
'b'
share
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How do I loop through or enumerate a JavaScript object?
...have to make sure that the key you get is an actual property of an object, and doesn't come from the prototype.
Here is the snippet:
var p = {
"p1": "value1",
"p2": "value2",
"p3": "value3"
};
for (var key in p) {
if (p.hasOwnProperty(key)) {
console.log(key + "...
Test if a variable is a list or tuple
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Go ahead and use isinstance if you need it. It is somewhat evil, as it excludes custom sequences, iterators, and other things that you might actually need. However, sometimes you need to behave differently if someone, for instance, ...