7.4.6 The break Statement

The break statement jumps out of the innermost for, while, or do loop that encloses it. The following example finds the smallest divisor of any integer, and also identifies prime numbers:

# find smallest divisor of num
{
   num = $1
   for (div = 2; div * div <= num; div++) {
     if (num % div == 0)
       break
   }
   if (num % div == 0)
     printf "Smallest divisor of %d is %d\n", num, div
   else
     printf "%d is prime\n", num
}

When the remainder is zero in the first if statement, awk immediately breaks out of the containing for loop. This means that awk proceeds immediately to the statement following the loop and continues processing. (This is very different from the exit statement, which stops the entire awk program. See section The exit Statement.)

The following program illustrates how the condition of a for or while statement could be replaced with a break inside an if:

# find smallest divisor of num
{
  num = $1
  for (div = 2; ; div++) {
    if (num % div == 0) {
      printf "Smallest divisor of %d is %d\n", num, div
      break
    }
    if (div * div > num) {
      printf "%d is prime\n", num
      break
    }
  }
}

The break statement is also used to break out of the switch statement. This is discussed in The switch Statement.

The break statement has no meaning when used outside the body of a loop or switch. However, although it was never documented, historical implementations of awk treated the break statement outside of a loop as if it were a next statement (see section The next Statement). (d.c.) Recent versions of Brian Kernighan’s awk no longer allow this usage, nor does gawk.