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parseInt vs unary plus, when to use which?
..., here are a few differences I know of:
An empty string "" evaluates to a 0, while parseInt evaluates it to NaN. IMO, a blank string should be a NaN.
+'' === 0; //true
isNaN(parseInt('',10)); //true
The unary + acts more like parseFloat since it also accepts decimals.
parseInt on...
c++提取复数的实部和虚部 - C/C++ - 清泛网 - 专注C/C++及内核技术
...arse(COMPLEX * cp, const char * strCplx, const int len)
{
memset(cp, 0, sizeof(COMPLEX));
char buf[MAX_BUF_LEN];
int signPos = -1, // +/-号位置
iPos = -1; // 结尾的i的位置
for (int i = len-1; i >-1; i--)
{
if ('i' == strCplx[i])
...
List comprehension vs map
... map when using exactly the same function:
$ python -mtimeit -s'xs=range(10)' 'map(hex, xs)'
100000 loops, best of 3: 4.86 usec per loop
$ python -mtimeit -s'xs=range(10)' '[hex(x) for x in xs]'
100000 loops, best of 3: 5.58 usec per loop
An example of how performance comparison gets completely r...
C dynamically growing array
...lSize) {
a->array = malloc(initialSize * sizeof(int));
a->used = 0;
a->size = initialSize;
}
void insertArray(Array *a, int element) {
// a->used is the number of used entries, because a->array[a->used++] updates a->used only *after* the array has been accessed.
// Th...
initialize a vector to zeros C++/C++11
...eed initialization lists for that:
std::vector<int> vector1(length, 0);
std::vector<double> vector2(length, 0.0);
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Java regular expression OR operator
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edited Jan 9 '10 at 0:57
answered Jan 9 '10 at 0:46
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How do you validate a URL with a regular expression in Python?
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answered May 6 '09 at 1:09
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Hour from DateTime? in 24 hours format
...he hour but show it in 24 hours format.
For example:
If the hour is 2:20:23 p.m. i want to convert it to 14:20 and that's it.
...
What is the Scala annotation to ensure a tail recursive function is optimized?
...ps and tricks):
C:\Prog\Scala\tests>scala
Welcome to Scala version 2.8.0.RC5 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_18).
Type in expressions to have them evaluated.
Type :help for more information.
scala> import scala.annotation.tailrec
import scala.annotation.tailrec
scala> clas...
Reading output of a command into an array in Bash
...=$'\n' read -r -d '' -a my_array < <( my_command && printf '\0' )
Please make sure you use exactly this form, i.e., make sure you have the following:
IFS=$'\n' on the same line as the read statement: this will only set the environment variable IFS for the read statement only. So it...