Editing NOP (code) (section)

=== C and derivatives ===
The simplest NOP statement in C is the ''null statement'', which is just a semi-colon in a context requiring a statement.

Most C compilers generate no code for null statements, which has historical and performance reasons. 
   ;
An empty block (compound statement) is also a NOP, and may be more legible, but will still have no code generated for it by the compiler.
   {}
In some cases, such as the body of a function, a block must be used, but this can be empty. In C, statements cannot be empty—simple statements must end with a <code>;</code> (semicolon) while compound statements are enclosed in <code>{}</code> (braces), which does not itself need a following semicolon. Thus in contexts where a statement is grammatically required, some such null statement can be used.

The null statement is useless by itself, but it can have a syntactic use in a wider context, e.g., within the context of a loop:
<syntaxhighlight lang="c">
  while (getchar() != '\n') {}
</syntaxhighlight>
alternatively,
<syntaxhighlight lang="c">

  while (getchar() != '\n')
      ;
</syntaxhighlight>
or more tersely:
<syntaxhighlight lang="c">

  while (getchar() != '\n');
</syntaxhighlight>
(note that the last form may be confusing, and as such generates a warning with some compilers or compiler options, as semicolon usually indicates an end of function call instruction when placed after a parenthesis on the end of line).

The above code continues calling the function <code>getchar()</code> until it returns a <code>\n</code> (newline) character, essentially fast-forwarding the current reading location of standard input to the beginning of next line.