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What is the difference between LR, SLR, and LALR parsers?
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SLR, LALR and LR parsers can all be implemented using exactly the same table-driven machinery.
Fundamentally, the parsing algorithm collects the next input token T, and consults the current state S (and associated lookahead, GOTO, and reduction tables...
PostgreSQL: Difference between text and varchar (character varying)
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There is no difference, under the hood it's all varlena (variable length array).
Check this article from Depesz: http://www.depesz.com/index.php/2010/03/02/charx-vs-varcharx-vs-varchar-vs-text/
A couple of highlights:
To sum it all up:
char(n) – takes t...
Select rows which are not present in other table
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There are basically 4 techniques for this task, all of them standard SQL.
NOT EXISTS
Often fastest in Postgres.
SELECT ip
FROM login_log l
WHERE NOT EXISTS (
SELECT -- SELECT list mostly irrelevant; can just be empty in Postgr...
Python: How to get stdout after running os.system? [duplicate]
I want to get the stdout in a variable after running the os.system call.
6 Answers
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New to unit testing, how to write great tests? [closed]
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My tests just seems so tightly bound to the method (testing all codepath, expecting some inner methods to be called a number of times, with certain arguments), that it seems that if I ever refactor the method, the tests will fail even if the final behavior of the method did not change...
Warn user before leaving web page with unsaved changes
...firmationMessage; //Gecko + Webkit, Safari, Chrome etc.
});
};
Then calling the setter when submitting:
<form method="post" onsubmit="setFormSubmitting()">
<input type="submit" />
</form>
But read on...
Long, correct answer:
You also don't want to show this mess...
Run an untrusted C program in a sandbox in Linux that prevents it from opening files, forking, etc.?
...interactively and in automatic mode. It has a ptrace()-based backend which allows its use on a Linux system without special privileges, as well as a far faster and more poweful backend which requires patching the kernel.
It is also possible to create a sandbox on Unix-like systems using chroot(1), ...
What exactly is Apache Camel?
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If you have 5 to 10 minutes, I generally recommend people to read this Integration with Apache Camel by Jonathan Anstey. It's a well written piece which gives a brief introduction to and overview of some of Camel's concepts, and it implements a use case with co...
In C, how should I read a text file and print all strings
...igned.
If you want to read the file in chunks, but without dynamic memory allocation, you can do:
#define CHUNK 1024 /* read 1024 bytes at a time */
char buf[CHUNK];
FILE *file;
size_t nread;
file = fopen("test.txt", "r");
if (file) {
while ((nread = fread(buf, 1, sizeof buf, file)) > 0)
...
What is the purpose of a self executing function in javascript?
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It's all about variable scoping. Variables declared in the self executing function are, by default, only available to code within the self executing function. This allows code to be written without concern of how variables are nam...