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Convert char to int in C and C++
...-> 1, etc, you can write
char a = '4';
int ia = a - '0';
/* check here if ia is bounded by 0 and 9 */
Explanation:
a - '0' is equivalent to ((int)a) - ((int)'0'), which means the ascii values of the characters are subtracted from each other. Since 0 comes directly before 1 in the ascii table (...
Get all attributes of an element using jQuery
...array
// of attribute nodes, which contain both the name and value
if(this.specified) {
console.log(this.name, this.value);
}
});
});
What you can also do is extending .attr so that you can call it like .attr() to get a plain object of all attributes:
(function(old) {
$.fn...
How to access environment variable values?
...mes you might need to see a complete list!
# using get will return `None` if a key is not present rather than raise a `KeyError`
print(os.environ.get('KEY_THAT_MIGHT_EXIST'))
# os.getenv is equivalent, and can also give a default value instead of `None`
print(os.getenv('KEY_THAT_MIGHT_EXIST', defa...
How to access component methods from “outside” in ReactJS?
...t;
</div>
);
}
}
Note: This will only work if the child component is declared as a class, as per documentation found here: https://facebook.github.io/react/docs/refs-and-the-dom.html#adding-a-ref-to-a-class-component
Update 2019-04-01: Changed example to use a class ...
Disable Required validation attribute under certain circumstances
I was wondering if it is possible to disable the Required validation attribute in certain controller actions. I am wondering this because on one of my edit forms I do not require the user to enter values for fields that they have already specified previously. However I then implement logic that when...
Socket.IO - how do I get a list of connected sockets/clients?
... // the default namespace is "/"
, ns = io.of(namespace ||"/");
if (ns) {
for (var id in ns.connected) {
if(roomId) {
var index = ns.connected[id].rooms.indexOf(roomId);
if(index !== -1) {
res.push(ns.connected[id]);
...
Using ls to list directories and their total sizes
...dable *
Explanation:
du: Disk Usage
-s: Display a summary for each specified file. (Equivalent to -d 0)
-h: "Human-readable" output. Use unit suffixes: Byte, Kibibyte (KiB), Mebibyte (MiB), Gibibyte (GiB), Tebibyte (TiB) and Pebibyte (PiB). (BASE2)
...
Make: how to continue after a command fails?
...
For example,
clean:
-rm -f *.o
This causes rm to continue even if it is unable to remove a file.
All examples are with rm, but are applicable to any other command you need to ignore errors from (i.e. mkdir).
sh...
Where do I find the current C or C++ standard documents?
...99, C++98, C++03 will be hard to find for purchase from a standards body. If you need an old revision of a standard, check Techstreet as one possible source. For example, it can still provide the Canadian version CAN/CSA-ISO/IEC 9899:1990 standard in PDF, for a fee.
Non-PDF electronic versions of...
Declare slice or make slice?
In Go, what is the difference between var s []int and s := make([]int, 0) ?
4 Answers
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