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How to TryParse for Enum value?
... = Enum.ToObject(type, ul);
return true;
}
private static char[] _enumSeperators = new char[] { ',', ';', '+', '|', ' ' };
private static object EnumToObject(Type underlyingType, string input)
{
if (underlyingType == typeof(int))
{
int s;
...
What is the bit size of long on 64-bit Windows?
...bit' and 'long, pointers are 64-bit'.
Type ILP64 LP64 LLP64
char 8 8 8
short 16 16 16
int 64 32 32
long 64 64 32
long long 64 64 64
pointer 64 64 64
The ILP64 sys...
Which is fastest? SELECT SQL_CALC_FOUND_ROWS FROM `table`, or SELECT COUNT(*)
...irm this - I just updated a query with 4 joins on a 168,000 row database. Selecting just the first 100 rows with a SQL_CALC_FOUND_ROWS took over 20 seconds; using a separate COUNT(*) query took under 5 seconds (for both count + results queries).
– Sam Dufel
Ju...
How do SQL EXISTS statements work?
... criteria -- this is why it can be faster than IN. Also be aware that the SELECT clause in an EXISTS is ignored - IE:
SELECT s.*
FROM SUPPLIERS s
WHERE EXISTS (SELECT 1/0
FROM ORDERS o
WHERE o.supplier_id = s.supplier_id)
...should hit a division by zero error...
C default arguments
...Yes. :-) But not in a way you would expect.
int f1(int arg1, double arg2, char* name, char *opt);
int f2(int arg1, double arg2, char* name)
{
return f1(arg1, arg2, name, "Some option");
}
Unfortunately, C doesn't allow you to overload methods so you'd end up with two different functions. Still...
Is multiplication and division using shift operators in C actually faster?
... back, I benchmarked two
versions of my hashing algorithm:
unsigned
hash( char const* s )
{
unsigned h = 0;
while ( *s != '\0' ) {
h = 127 * h + (unsigned char)*s;
++ s;
}
return h;
}
and
unsigned
hash( char const* s )
{
unsigned h = 0;
while ( *s != '\0' ...
How do I read an entire file into a std::string in C++?
...os_type fileSize = ifs.tellg();
ifs.seekg(0, ios::beg);
vector<char> bytes(fileSize);
ifs.read(bytes.data(), fileSize);
return string(bytes.data(), fileSize);
}
This solution resulted in about 20% faster execution times than the other answers presented here, when taking the...
How to exclude this / current / dot folder from find “type d”
...his particular case (.), golfs better than the mindepth solution (24 vs 26 chars), although this is probably slightly harder to type because of the !.
To exclude other directories, this will golf less well and requires a variable for DRYness:
D="long_name"
find "$D" ! -path "$D" -type d
My decis...
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_id, COUNT(subordinate.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doe...
How to select a single field for all documents in a MongoDB collection?
...nt such as:
db.student.find({}, {roll:1, _id:0})
The above statement will select all documents in the students collection, and the returned document will return only the roll field (and exclude the _id).
If we don't mention _id:0 the fields returned will be roll and _id. The '_id' field is always d...