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What is x after “x = x++”?
...gning the old value of x back into itself.
x = x++;
x++ increments x and returns its old value.
x = assigns the old value back to itself.
So in the end, x gets assigned back to its initial value.
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How to format strings using printf() to get equal length in the output?
...o functions, one which produces messages like Starting initialization... and another which checks return codes and outputs "Ok" , "Warning" or "Error" . However, the output that is produced is of the different length:
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How to escape a JSON string to have it in a URL?
...forum/?fromgroups=#!topic/nodejs/ivdZuGCF86Q
shows benchmarks for encoding and parsing.
Note: After testing, it looks like jsurl.js library uses ECMAScript 5 functions such as Object.keys, Array.map, and Array.filter. Therefore, it will only work on modern browsers (no ie 8 and under). However, are...
Assign multiple columns using := in data.table, by group
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Thanks for this answer and the examples. How should I modify the following line in order to get two columns for each objectName from the dim output, rather than one column with two rows? data.table(objectName=ls())[,c("rows","cols"):=dim(get(objec...
Maximum size of an Array in Javascript
Context: I'm building a little site that reads an rss feed, and updates/checks the feed in the background. I have one array to store data to display, and another which stores ID's of records that have been shown.
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The input is not a valid Base-64 string as it contains a non-base 64 character
I have a REST service that reads a file and sends it to another console application after converting it to Byte array and then to Base64 string. This part works, but when the same stream is received at the application, it gets manipulated and is no longer a valid Base64 string. Some junk characters ...
How to add a changed file to an older (not last) commit in Git
I have changed several things over the last hour and committed them step by step, but I just realized I've forgot to add a changed file some commits ago.
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How is “=default” different from “{}” for default constructor and destructor?
...om simply doing {}. With the latter, the function becomes "user-provided". And that changes everything.
This is a trivial class by C++11's definition:
struct Trivial
{
int foo;
};
If you attempt to default construct one, the compiler will generate a default constructor automatically. Same goes...
What is the difference between git clone and checkout?
What is the difference between git clone and git checkout ?
5 Answers
5
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How to add “on delete cascade” constraints?
... You have to drop the constraint first, then add the correct version. In standard SQL, I believe the easiest way to do this is to
start a transaction,
drop the foreign key,
add a foreign key with on delete cascade, and finally
commit the transaction
Repeat for each foreign key you want to change...