Selecting entire function definition in Vim

To delete an entire function, including its definition, such as:

function tick() {
        // ... 
}

• Move to the line with the function name.
• Move the cursor to the opening brace, f{ should do it, or simply $.
• Press V%d (Visual line, move to matching pair, delete)

If your functions look like this:

function tick() 
{
        // ... 
}

• Move to the line with the function name.
• Press J (join the current line with line bellow. This also puts your cursor at the last character on the resulting line, {, just the one we need for the next command.)
• Press V%d (Visual line, move to matching pair, delete.)

or

• Move to the line with the function name.
• Press V[Down]%d (Visual line, move one line down, move to matching pair, delete.)

As is common in Vim, there are a bunch of ways!

Note that the first two solutions depend on an absence of blank lines.

• If your cursor is on the line with the function name, try d}. It will delete everything to the next block (i.e. your function body).

• Within the function body itself, dap will delete the 'paragraph'.

• You can delete a curly brace block with da}. (If you like this syntax, I recommend Tim Pope's fantastic surround.vim, which adds more features with a similar feel).

• You could also try using regular expressions to delete until the next far left-indented closing curly brace: d/^}Enter

• ]] and [[ move to the next/previous first-column curly brace (equivalent to using / and ? with that regex I mentioned above. Combine with the d motion, and you acheive the same effect. In addons like Python-mode, these operators are redefined to mean exactly what you're looking for: move from function to function.

How to delete the whole block, header included

If you're on the header/name, or the line before the block, da} should do the trick.

If you're below a block, you can also make use of the handy 'offset' feature of a Vim search. d?^{?-1 will delete backwards to one line before the first occurrence of a first-column opening curly brace. This command's a bit tricky to type. Maybe you could make a <leader> shortcut out of it.

Plugins

I don't do much C programming in Vim, but there are surely plugins to help with such a thing. Try Vim Scripts or their mirror at GitHub.