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Debug Error \"pure virtual function call\" 原因解析 - 更多技术 - 清泛...
...
public:
virtual void virtualFunc(){}
};
Base* pB = new Derived;
__try
{
delete pB; // . . . b)
pB = NULL;
}
__except(EXCEPTION_EXECUTE_HANDLER){
}
pB->virtualFunc(); // . . . c)
在b)处析构Derived对象的时候，在其基类析构函数中a)处抛出了...
how to change any data type into a string in python
... you're writing your own class and you want str to work for you, add:
def __str__(self):
return "Some descriptive string"
print str(myObj) will call myObj.__str__().
repr is a similar method, which generally produces information on the class info. For most core library object, repr produces ...
Backwards migration with Django South
...r app should have a migrations directory, with files in it named like
0000_initial.py
0001_added_some_fields.py
0002_added_some_more_fields.py
0003_deleted_some_stuff.py
Normally, when you run ./manage.py migrate your_app, South runs all new migrations, in order. (It looks at the database tables ...
How to generate random number with the specific length in python
... use an arbitrary number of digits:
from random import randint
def random_with_N_digits(n):
range_start = 10**(n-1)
range_end = (10**n)-1
return randint(range_start, range_end)
print random_with_N_digits(2)
print random_with_N_digits(3)
print random_with_N_digits(4)
Output:
33
124
...
Find the most common element in a list
...ponents. Consider for example:
import itertools
import operator
def most_common(L):
# get an iterable of (item, iterable) pairs
SL = sorted((x, i) for i, x in enumerate(L))
# print 'SL:', SL
groups = itertools.groupby(SL, key=operator.itemgetter(0))
# auxiliary function to get "quality"...
How Many Seconds Between Two Dates?
...Z, NN, EE, 0, 0, 0, 0);
var dif = t1.getTime() - t2.getTime();
var Seconds_from_T1_to_T2 = dif / 1000;
var Seconds_Between_Dates = Math.abs(Seconds_from_T1_to_T2);
A handy source for future reference is the MDN site
Alternatively, if your dates come in a format javascript can parse
var dif = Da...
How to document class attributes in Python? [closed]
...speed exceeding that of an unladen swallow.
Attributes:
flight_speed The maximum speed that such a bird can attain.
nesting_grounds The locale where these birds congregate to reproduce.
"""
flight_speed = 691
nesting_grounds = "Throatwarbler Man Grove"
I think...
Create a CSV File for a user in PHP
...!== false || strpos($string, "\n") !== false) {
$string = '"' . str_replace('"', '""', $string) . '"';
}
return $string;
}
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CSS styling in Django forms
...aken from my answer to:
How to markup form fields with <div class='field_type'> in Django
class MyForm(forms.Form):
myfield = forms.CharField(widget=forms.TextInput(attrs={'class' : 'myfieldclass'}))
or
class MyForm(forms.ModelForm):
class Meta:
model = MyModel
def __i...
Create or write/append in text file
...
Try something like this:
$txt = "user id date";
$myfile = file_put_contents('logs.txt', $txt.PHP_EOL , FILE_APPEND | LOCK_EX);
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