If you use Emacs for programming in the C language;, you can
get it to do all the indentation for you automatically. Files whose
names end in ``.c '' or ``.h'' are automatically brought
up in c-mode. This means that certain special editing commands,
useful for writing C-programs, are available. In C-mode, 
is
bound to c-indent-command. This means that hitting the
key does not actually insert a tab character. Instead, if
you hit anywhere on a line, Emacs automatically indents
that line correctly for its location in the program. This implies
that Emacs knows something about C syntax, which it does (although
nothing about semantics--it cannot insure that your program has no
errors!)
In order to do this, it assumes that the previous lines are indented correctly. That means that if the preceding line is missing a parenthesis, semicolon, curly brace, or whatever, Emacs will indent the current line in a funny way. When you see it do that, you will know to look for a punctuation mistake on the line above.
You can use this feature to check that you have punctuated
your programs correctly--instead of reading through the entire
program looking for problems, just start indenting lines from the top
down with , and when something indents oddly, check the
lines just before it. In other words, let Emacs do the work for you!