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Number.sign() in javascript
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More elegant version of fast solution:
var sign = number?number<0?-1:1:0
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How to validate an Email in PHP?
...LTER_VALIDATE_EMAIL)
PHP Manual filter_var()
Available in PHP >= 5.2.0
If you don't want to change your code that relied on your function, just do:
function isValidEmail($email){
return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
}
Note: For other uses (where you need Regex)...
C char array initialization
... how you initialize an array, but for:
The first declaration:
char buf[10] = "";
is equivalent to
char buf[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
The second declaration:
char buf[10] = " ";
is equivalent to
char buf[10] = {' ', 0, 0, 0, 0, 0, 0, 0, 0, 0};
The third declaration:
char buf[...
How can I profile C++ code running on Linux?
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1440
If your goal is to use a profiler, use one of the suggested ones.
However, if you're in a hurry...
Moving decimal places over in a double
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190
If you use double or float, you should use rounding or expect to see some rounding errors. If yo...
How can I profile Python code line-by-line?
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120
I believe that's what Robert Kern's line_profiler is intended for. From the link:
File: pyston...
What Process is using all of my disk IO
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You're looking for iotop (assuming you've got kernel >2.6.20 and Python 2.5). Failing that, you're looking into hooking into the filesystem. I recommend the former.
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Designing function f(f(n)) == -n
...w about:
f(n) = sign(n) - (-1)n * n
In Python:
def f(n):
if n == 0: return 0
if n >= 0:
if n % 2 == 1:
return n + 1
else:
return -1 * (n - 1)
else:
if n % 2 == 1:
return n - 1
else:
return -1 * (n ...
How to iterate through two lists in parallel?
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edited Jun 9 '19 at 20:46
Tobias Kolb
9461111 silver badges2626 bronze badges
answered Nov 2 '09 at...
How do I check to see if a value is an integer in MySQL?
...lar expression. Simply do
select field from table where field REGEXP '^-?[0-9]+$';
this is reasonably fast. If your field is numeric, just test for
ceil(field) = field
instead.
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