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Can code that is valid in both C and C++ produce different behavior when compiled in each language?
...in different values in i in C and C++:
int i = sizeof('a');
See Size of character ('a') in C/C++ for an explanation of the difference.
Another one from this article:
#include <stdio.h>
int sz = 80;
int main(void)
{
struct sz { char c; };
int val = sizeof(sz); // sizeof(in...
Simplest way to do a recursive self-join?
...
WITH q AS
(
SELECT *
FROM mytable
WHERE ParentID IS NULL -- this condition defines the ultimate ancestors in your chain, change it as appropriate
UNION ALL
SELECT m.*
FROM mytable m
...
SQL query return data from multiple tables
...rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> select * from colors;
+----+-------+----------+
| id | color | paint |
+----+-------+----------+
| 1 | Red | Metallic |
| 2 | Green | Gloss |
| 3 | Blue | Metallic |
| 4 | White | Gloss |
| 5 | Black | Gloss ...
MySQL Great Circle Distance (Haversine formula)
...ults. To search by kilometers instead of miles, replace 3959 with 6371.
SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) )
* cos( radians( lng ) - radians(-122) ) + sin( radians(37) ) * sin(radians(lat)) ) ) AS distance
FROM markers
HAVING distance < 25
ORDER BY distance ...
Linq: What is the difference between Select and Where
The Select and Where methods are available in Linq. What should every developer know about these two methods? For example: when to use one over the other, any advantages of using one over the other, etc.
...
MySQL: Fastest way to count number of rows
...s.
The solution is SQL_CALC_FOUND_ROWS. This is usually used when you are selecting rows but still need to know the total row count (for example, for paging).
When you select data rows, just append the SQL_CALC_FOUND_ROWS keyword after SELECT:
SELECT SQL_CALC_FOUND_ROWS [needed fields or *] FROM t...
MySQL Insert Where query
...INSERT INTO Users(weight, desiredWeight)
VALUES (160,145)
INSERT using a SELECT statement
INSERT INTO Users(weight, desiredWeight)
SELECT weight, desiredWeight
FROM AnotherTable
WHERE id = 1
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How to print to console when using Qt
... stream than stderr.)
NOTE: All of the Qt print methods assume that const char* arguments are ISO-8859-1 encoded strings with terminating \0 characters.
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SQL - using alias in Group By
... following order:
FROM clause
WHERE clause
GROUP BY clause
HAVING clause
SELECT clause
ORDER BY clause
For most relational database systems, this order explains which names (columns or aliases) are valid because they must have been introduced in a previous step.
So in Oracle and SQL Server, you...
What is the difference between std::array and std::vector? When do you use one over other? [duplicat
...inter to an array; e.g., C library routines. (As an aside, std::vector<char> buf(8192); is a great way to allocate a local buffer for calls to read/write or similar without directly invoking new.)
That said, the lack of that extra level of indirection, plus the compile-time constant size, ca...