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Should I use static_cast or reinterpret_cast when casting a void* to whatever
...ore type safety and just cast from A to B”.
However, this doesn’t actually describe the effect of a reinterpret_cast. Rather, reinterpret_cast has a number of meanings, for all of which holds that “the mapping performed by reinterpret_cast is implementation-defined.” [5.2.10.3]
But in the ...
How can I hash a password in Java?
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You can actually use a facility built in to the Java runtime to do this. The SunJCE in Java 6 supports PBKDF2, which is a good algorithm to use for password hashing.
byte[] salt = new byte[16];
random.nextBytes(salt);
KeySpec spec = new...
Using std Namespace
...efined vector.
I am always against using using namespace std;. It imports all sorts of names into the global namespace and can cause all sorts of non-obvious ambiguities.
Here are some common identifiers that are in the std namespace: count, sort, find, equal, reverse. Having a local variable call...
What is ActiveMQ used for - can we apply messaging concept using a Database?
...that up communicating thousands of messages per second, Databases tend to fall over.
Message-oriented middle-ware [MOM] like ActiveMQ on the other hand are built to handle those use cases.
They assume that messages in a healthy system will be deleted very quickly and can do optimizations to avoid t...
How to get the original value of an attribute in Rails
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Reading/parsing Excel (xls) files with Python
... pandas is using xlrd to do the reading; you will need to also install xlrd as a dependency
– congusbongus
Jul 16 '19 at 1:24
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MySQL Creating tables with Foreign Keys giving errno: 150
... CONSTRAINT's ON DELETE rule is SET NULL make sure the foreign key can actually be NULL! I spent 30 minutes reading this answer over and over, making sure my tables met the conditions but still getting Error 150. Then I noticed my FK was a NOT NULL field meaning the rule was impossible to apply.
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what is .netrwhist?
...riting files across networks. .netrwhist is a history file which maintains all the directories that were modified. So whenever you modify the contents of ~/.vim it adds one entry in .netrwhist
A sample .netrwhist is as shown
let g:netrw_dirhistmax =10
let g:netrw_dirhist_cnt =6
let g:netrw_dirhis...
How to pass password to scp?
I know it is not recommended, but is it at all possible to pass the user's password to scp?
17 Answers
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Define make variable at rule execution time
...r are evaluated. In order to create the directory only when out.tar is actually fired, you need to move the directory creation down into the steps:
out.tar :
$(eval TMP := $(shell mktemp -d))
@echo hi $(TMP)/hi.txt
tar -C $(TMP) cf $@ .
rm -rf $(TMP)
The eval function evaluates a...