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Adding a new SQL column with a default value
...
Try this:
ALTER TABLE table1 ADD COLUMN foo INT DEFAULT 0;
From the documentation that you linked to:
ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name
alter_specification [, alter_specification] ...
alter_specification:
...
ADD [COLUMN] (col_name colum...
Array to Hash Ruby
... @tester, the * is called the splat operator. It takes an array and converts it a literal list of items. So *[1,2,3,4] => 1, 2, 3, 4. In this example, the above is equivalent to doing Hash["item 1", "item 2", "item 3", "item 4"]. And Hash has a [] method that accepts a list of arguments (m...
warning: implicit declaration of function
... the compiler has not seen a declaration ("prototype") yet.
For example:
int main()
{
fun(2, "21"); /* The compiler has not seen the declaration. */
return 0;
}
int fun(int x, char *p)
{
/* ... */
}
You need to declare your function before main, like this, either directly or ...
Passing a method as a parameter in Ruby
...ng. It's worth noting that you call method( :<name> ) just once when converting your method name to a callable symbol. You can store that result in a variable or a parameter and keep passing it to child functions like any other variable from then on...
– user1115652
...
Using Linq to get the last N elements of a collection?
...c IEnumerable<T> TakeLast<T>(this IEnumerable<T> source, int N)
{
return source.Skip(Math.Max(0, source.Count() - N));
}
}
A brief note on performance:
Because the call to Count() can cause enumeration of certain data structures, this approach has the risk of cau...
How can I hash a password in Java?
...spec).getEncoded();
Base64.Encoder enc = Base64.getEncoder();
System.out.printf("salt: %s%n", enc.encodeToString(salt));
System.out.printf("hash: %s%n", enc.encodeToString(hash));
Here's a utility class that you can use for PBKDF2 password authentication:
import java.security.NoSuchAlgorithmExcep...
Utilizing the GPU with c# [closed]
...ths ago or so, and did get it working though it took a little bit of work. Converts C# kernel code to cuda at compile time. Unfortunately their website has been down and their github hasn't been updated for a couple of years, which might indicate the project is dead....
Cudafy - Open source and very...
How do I remove an item from a stl vector with a certain value?
...e extra elements that are now at the end of the container:
std::vector<int> vec;
// .. put in some values ..
int int_to_remove = n;
vec.erase(std::remove(vec.begin(), vec.end(), int_to_remove), vec.end());
share
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Picking a random element from a set
How do I pick a random element from a set?
I'm particularly interested in picking a random element from a
HashSet or a LinkedHashSet, in Java.
Solutions for other languages are also welcome.
...
Printing the correct number of decimal points with cout
I have a list of float values and I want to print them with cout with 2 decimal places.
12 Answers
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