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How are Python's Built In Dictionaries Implemented?
...49)
When adding entries to the table, we start with some slot, i, that is based on the hash of the key. CPython initially uses i = hash(key) & mask (where mask = PyDictMINSIZE - 1, but that's not really important). Just note that the initial slot, i, that is checked depends on the hash of the k...
How to find out which package version is loaded in R?
... LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] graphics grDevices utils datasets stats grid methods base
other attached packages:
[1] ggplot2_0.9.0 reshape2_1.2.1 plyr_1.7.1
loaded via a namespace (and not attached):
[1] co...
Hash String via SHA-256 in Java
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@Sajjad Use your favorite base64 encoding function. I like the one in Apache Commons personally.
– Brendan Long
Oct 22 '13 at 19:34
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Will the base class constructor be automatically called?
Would the age of customer be 2? It seems like the base class's constructor will be called no matter what. If so, why do we need to call base at the end sometimes?
...
Do try/catch blocks hurt performance when exceptions are not thrown?
...r version), but it was no difference in the Release version.
Conclution:
Based on these test, I think we can say that Try/Catch does have a small impact on performance.
EDIT:
I tried to increase the loop value from 10000000 to 1000000000, and ran again in Release to get some differences in the re...
How do I analyze a program's core dump file with GDB when it has command-line parameters?
...2'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000564583cf2759 in myfunc (i=3) at main.c:7
7 *(int*)(NULL) = i; /* line 7 */
(gdb) bt
#0 0x0000564583cf2759 in myfunc (i=3) at main.c:7
#1 0x0000564583cf2858 in main (argc=3, argv=0x7ffcca4effa8) at main.c:2
So not...
How to run a program without an operating system?
...n:
an x86 Lenovo Thinkpad T430 laptop with UEFI BIOS 1.16 firmware
an ARM-based Raspberry Pi 3
We will also try them out on the QEMU emulator as much as possible, as that is safer and more convenient for development. The QEMU tests have been on an Ubuntu 18.04 host with the pre-packaged QEMU 2.11....
Best practices for circular shift (rotate) operations in C++
...motion rules mean that rotl_template(u16 & 0x11UL, 7) would do a 32 or 64-bit rotate, not 16 (depending on the width of unsigned long). Even uint16_t & uint16_t is promoted to signed int by C++'s integer-promotion rules, except on platforms where int is no wider than uint16_t.
On x86, th...
Python dictionary: Get list of values for list of keys
...
A little speed comparison:
Python 2.7.11 |Anaconda 2.4.1 (64-bit)| (default, Dec 7 2015, 14:10:42) [MSC v.1500 64 bit (AMD64)] on win32
In[1]: l = [0,1,2,3,2,3,1,2,0]
In[2]: m = {0:10, 1:11, 2:12, 3:13}
In[3]: %timeit [m[_] for _ in l] # list comprehension
1000000 loops, best of 3...
What is the fastest/most efficient way to find the highest set bit (msb) in an integer in C?
...lt; N), finding the position (N) of the highest set bit is the integer log base 2 of that integer.
http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious
unsigned int v;
unsigned r = 0;
while (v >>= 1) {
r++;
}
This "obvious" algorithm may not be transparent to everyone...