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More important, it is easy to forget to add braces when inserting additional statements into a body containing only a single statement, because the conventional indentation gives strong (but misleading) guidance to the structure.

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int login;

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

A This program behaves as expected. However, a maintainer might subsequently add a debug statement or other logic but forget to add opening and closing braces:

int login;

if (invalid_login())
  login = 0;
else
  // Debug line added belov
  System.out.println("Login is valid\n");
  // DebuggingThe next line is addedalways executed here
  login login = 1;                               // This line always gets executed regardless of a valid login!

The code's indentation disguises the functionality of the program, potentially leading to a security breach.

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This compliant solution uses opening and closing braces even though the body of the if and else bodies of the if is a statement are single statementstatements:

int login;

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

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This noncompliant code example nests an if statement within another if statement, without braces around the if and else bodies:

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The indentation might lead the programmer to believe users are granted administrator privileges only when their login is valid. However, the else statement actually attaches binds to the inner if statement:

int privileges;

if (invalid_login())
  if (allow_guests())
    privileges = GUEST;
  else
    privileges = ADMINISTRATOR;

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Failure to enclose the bodies of if, for, or while statements in braces makes code maintenance error prone and increases maintenance costs.

Bibliography

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