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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...
Declare slice or make slice?
In Go, what is the difference between var s []int and s := make([]int, 0) ?
4 Answers
...
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...