Use of Caret Symbol (^) in Ruby

Use of caret symbol (^) in Ruby

It's a bitwise XOR operator.

For each bit in the binary representation of the operands, a bitwise XOR will get a 1 bit if one of the corresponding bits in the operands is 1, but not both, otherwise the XOR will get a 0 bit. Here's an example:

5     = 101
6     = 110
5 ^ 6 = 011 = 3

Caret in objective C

It depends on the context. In the example you show, it's used to denote a Block. The caret symbol is also the bitwise XOR operator in C-based languages — that's what most programmers would identify it as, so it's good to understand that it can be both depending on where it appears, much like *, etc.

And while we're suggesting references, one simply has to include Apple's official Blocks reference.

what is ^ used for in ruby?

In most programming languages, ^ is the XOR operator (Exclusive Or in Wikipedia). XOR is one of the most essential operations in the CPU, it often employed to zero registers (think of a ^= a) because it is fast and has a short opcode.

For the power function, you have to use e.g. ** (e.g. in ruby), java.lang.Math.pow, math.pow, pow etc.

In fact, I couldn't name a programming language that uses ^. It is used in LaTeX for formatting (as superscript, not power function, technically). But the two variants I see all the time are ** (as the power function is directly related to multiplication) and pow(base, exp).

Note that you can compute integer powers of 2 faster using shifts.

Preprocessor macro using caret ^ symbol at the start of an expression

It's a C block. It's quite like an anonymous function (in use, not in structure). You can read more about them on Mike Ash's site and in Apple's documentation.

Caret in objective C

It depends on the context. In the example you show, it's used to denote a Block. The caret symbol is also the bitwise XOR operator in C-based languages — that's what most programmers would identify it as, so it's good to understand that it can be both depending on where it appears, much like *, etc.

And while we're suggesting references, one simply has to include Apple's official Blocks reference.

how to display caret via rails link_to for dropdown in bootstrap

Try this,
<%= link_to 'Setup <b class="caret"></b>'.html_safe, root_path, :id => 'setupdrop', :'data-toggle' => 'dropdown', :class => 'dropdown-toggle' %>

What does :^ in reduce method mean?

The reduce method is used on arrays to combine all elements of that array into a single item.

The reduce method accepts a starting value and a block of code.

What you are using is a shorthand version of reduce which means the following:

numbers.reduce(&:^)

The & character will attempt to call the method on the argument itself when it is used as a last argument of a method call or definition. The ^ character signifies the bitwise XOR operator.

Inject is also an alias for reduce in Ruby.

You can read more here.

Does it ever make sense to have a caret or dollar sign in the middle of a regular expression?

Depending on the options, a ^ or a $ in the middle of a regular expression can cause a match:

>>> if re.search(r'xyz.^abc', "xyz\nabc", re.MULTILINE | re.DOTALL):
...    print "Matched"
...
Matched

MULTILINE makes ^ match the start of a line, even if that line isn't at the start of the string. DOTALL makes . match newlines.

(I can't find a way to make your exact examples match anything.)

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