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Redirect stderr and stdout in Bash
...
An extra hint: If you use this in a script, make sure it starts with #!/bin/bash rather than #!/bin/sh, since in requires bash.
– Tor Klingberg
Oct 1 '13 at 17:47
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Difference between objectForKey and valueForKey?
...ndexes, it uses keys to differentiate between items. A key is an arbitrary string you provide. No two objects can have the same key (just as no two objects in an NSArray can have the same index).
valueForKey: is a KVC method. It works with ANY class. valueForKey: allows you to access a property us...
Why is the asterisk before the variable name, rather than after the type?
...plication operator
And indirection is just a single meaning, there is no extra meaning for declaring a pointer, there is just indirection, which is what the dereference operation does, it performs an indirect access, so also within a statement like int *a; this is an indirect access (* means indir...
add created_at and updated_at fields to mongoose schemas
...mongoose version >= 4.0.
let ItemSchema = new Schema({
name: { type: String, required: true, trim: true }
},
{
timestamps: true
});
If set timestamps, mongoose assigns createdAt and updatedAt fields to your schema, the type assigned is Date.
You can also specify the timestamp fileds' name...
C# Entity-Framework: How can I combine a .Find and .Include on a Model Object?
...=> p.Blog).Load();
// Load the blog related to a given post using a string
context.Entry(post).Reference("Blog").Load();
var blog = context.Blogs.Find(1);
// Load the posts related to a given blog
context.Entry(blog).Collection(p => p.Posts).Load();
// Load the posts rel...
使用App Inventor扩展实现多点触控：Rotation Detector · App Inventor 2 中文网
...alizeAngle((float) Math.atan2(v2y, v2x),v2x,v2y);
Log.i("Rotate", String.format("Vector1 (%f,%f) Vector2 (%f,%f)", v1x,v1y,v2x,v2y));
float angle = (float)Math.toDegrees(angle1-angle2);
return angle;
}
private float normalizeAngle(float angle,float x, float y){
...
使用App Inventor扩展实现多点触控：Rotation Detector · App Inventor 2 中文网
...alizeAngle((float) Math.atan2(v2y, v2x),v2x,v2y);
Log.i("Rotate", String.format("Vector1 (%f,%f) Vector2 (%f,%f)", v1x,v1y,v2x,v2y));
float angle = (float)Math.toDegrees(angle1-angle2);
return angle;
}
private float normalizeAngle(float angle,float x, float y){
...
使用App Inventor扩展实现多点触控：Rotation Detector · App Inventor 2 中文网
...alizeAngle((float) Math.atan2(v2y, v2x),v2x,v2y);
Log.i("Rotate", String.format("Vector1 (%f,%f) Vector2 (%f,%f)", v1x,v1y,v2x,v2y));
float angle = (float)Math.toDegrees(angle1-angle2);
return angle;
}
private float normalizeAngle(float angle,float x, float y){
...
使用App Inventor扩展实现多点触控：Rotation Detector · App Inventor 2 中文网
...alizeAngle((float) Math.atan2(v2y, v2x),v2x,v2y);
Log.i("Rotate", String.format("Vector1 (%f,%f) Vector2 (%f,%f)", v1x,v1y,v2x,v2y));
float angle = (float)Math.toDegrees(angle1-angle2);
return angle;
}
private float normalizeAngle(float angle,float x, float y){
...
How to get key names from JSON using jq
... cat input.json | jq -r 'keys'
From jq help:
-r output raw strings, not JSON texts;
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