No error , No gain

When I make changes to a file in Git, how can I commit only some of the changes? For example, how could I commit only 15 lines out of 30 lines that have been changed in a file? You can use git add --patch (or -p for short), and git will begin to break down your file into what it thinks are sensible "hunks" (portions of the file). It will then prompt you with this question: Stage this hunk [y,n,q..

In PHP, strings are concatenated together as follows: $foo = "Hello"; $foo .= " World"; Here, $foo becomes "Hello World". How is this accomplished in Bash? foo="Hello" foo="${foo} World" echo "${foo}" > Hello World In general to concatenate two variables you can just write them one after another: a='Hello' b='World' c="${a} ${b}" echo "${c}" > Hello World codaddict Bash also supports a += operat..

How can I convert a String to an int in Java? My String contains only numbers, and I want to return the number it represents. For example, given the string "1234" the result should be the number 1234. String myString = "1234"; int foo = Integer.parseInt(myString); If you look at the Java documentation you'll notice the "catch" is that this function can throw a NumberFormatException, which of cou..

How can I check the existence of an element in jQuery? The current code that I have is this: if ($(selector).length > 0) { // Do something } Is there a more elegant way to approach this? Perhaps a plugin or a function? In JavaScript, everything is 'truthy' or 'falsy', and for numbers 0 means false, everything else true. So you could write: if ($(selector).length) You don't need that >0 part. Tim..

I've been told by others that writing using namespace std; in code is wrong, and that I should use std::cout and std::cin directly instead. Why is using namespace std; considered a bad practice? Is it inefficient or does it risk declaring ambiguous variables (variables that share the same name as a function in std namespace)? Does it impact performance? This is not related to performance at all...

The Python documentation seems unclear about whether parameters are passed by reference or value, and the following code produces the unchanged value 'Original' class PassByReference: def __init__(self): self.variable = 'Original' self.change(self.variable) print(self.variable) def change(self, var): var = 'Changed' Is there something I can do to pass the variable by actual reference? Arguments ..

I'm trying to write a function that either accepts a list of strings, or a single string. If it's a string, then I want to convert it to an array with just the one item so I can loop over it without fear of an error. So how do I check if the variable is an array? The method given in the ECMAScript standard to find the class of Object is to use the toString method from Object.prototype. if(Object..

Say I'm in a Git repository. I delete a file and commit that change. I continue working and make some more commits. Then, I find I need to restore that file. I know I can checkout a file using git checkout HEAD^ foo.bar, but I don't really know when that file was deleted. What would be the quickest way to find the commit that deleted a given filename? What would be the easiest way to get that fi..

What does the explicit keyword mean in C++? The compiler is allowed to make one implicit conversion to resolve the parameters to a function. What this means is that the compiler can use constructors callable with a single parameter to convert from one type to another in order to get the right type for a parameter. Here's an example class with a constructor that can be used for implicit conversio..

What is the difference between __str__ and __repr__ in Python? Alex summarized well but, surprisingly, was too succinct. First, let me reiterate the main points in Alex’s post: The default implementation is useless (it’s hard to think of one which wouldn’t be, but yeah) __repr__ goal is to be unambiguous __str__ goal is to be readable Container’s __str__ uses contained objects’ __repr__ Default ..