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MQTT与TCP的区别 - 创客硬件开发 - 清泛IT社区，为创新赋能！
一、MQTT与TCP的区别诞生时间TCP协议诞生于1974年冷战期间。MQTT诞生于1999年互联网初期，TCP协议比MQTT协议诞生早了25年。Ashton提出IoT概念也是在1999年，因此MQTT协议生逢其时。当时MIT Auto-ID Labs的Kevin Ashton为了把宝洁的供应链上的RF...
max value of integer
...hine to machine, on embedded systems the int can be 16 bit wide, though usually it is 32 bit.
The only requirement is that short int <= int <= long int by size. Also, there is a recommendation that int should represent the native capacity of the processor.
All types are signed. The unsigned...
How can I recognize touch events using jQuery in Safari for iPad? Is it possible?
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e is the event object that gets automatically passed to the handler. For the safari browser (and android too) it now contains an array of all the touches the user has made on the screen. Each touch has its own properties (x,y coords for example)
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How to find first element of array matching a boolean condition in JavaScript?
... var result = null;
arr.some(function(el, i) {
return test.call(ctx, el, i, arr) ? ((result = el), true) : false;
});
return result;
}
var result = find(someArray, isNotNullNorUndefined);
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Hide the cursor of an UITextField
...irst, store the text field's selected text range to an instance variable.
_textFieldSelectedTextRange = textField.selectedTextRange;
textField.selectedTextRange = nil; // hides caret
Then, when you want to unhide the caret, simply set the text field's selected text range back to what it was origi...
How to check if a value exists in a dictionary (python)
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it wasn't necesarry after all, unless run on bigger dict. I guess overhead in values() is caused by copying the value list and in viewvalues() by maintaining the view alive.
– soulcheck
Nov 21 '11 at 17:12
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Split a string by another string in C#
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I actually ended up changing my answer to this for 2 reasons: #1: To handle the splits I want to do I would need to use Regex.Escape, because my split string will often contain asterisks, etc. #2: While this program I'm writing...
Performance surprise with “as” and nullable types
...lable types, and I'm adding a section about using the "as" operator, which allows you to write:
10 Answers
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How to loop through a plain JavaScript object with the objects as members?
How can I loop through all members in a JavaScript object including values that are objects.
24 Answers
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Debug vs Release in CMake
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With CMake, it's generally recommended to do an "out of source" build. Create your CMakeLists.txt in the root of your project. Then from the root of your project:
mkdir Release
cd Release
cmake -DCMAKE_BUILD_TYPE=Release ..
make
And for Debug (...