Use braces for if, for, or while statement

Opening and closing braces for if, for, or while statements should always be used, even if said statement has only a single body line.

Braces help improve the uniformity, and therefore readability of code.

More importantly, when inserting an additional statement in a body containing only a single line, it is easy to forget to add braces when the indentation tends to give a strong (but probably misleading) guide to the structure.

Noncompliant Code Example

This noncompliant code example uses an if-else statement without braces to authenticate a user.

int login;

if (invalid_login())
  login = 0;
else
  login = 1;

The programmer adds a debugging statement to determine when the login is valid, but forgets to add opening and closing braces.

int login;

if (invalid_login())
  login = 0;
else
  printf("Login is valid\n");
  login = 1;

Due to the indentation of the code, it is difficult to tell that the code is not functioning as intended by the programmer, leading to a possible security breach.

h.3 Compliant Code Example
Opening and closing braces are used even when the body is a single statement.

int login;

if (invalid_login()) {
  login = 0;
} else {
  login = 1;
}