Editing For loop (section)

===Early exit and continuation===
Some languages may also provide other supporting statements, which when present can alter how the for-loop iteration proceeds. Common among these are the [[Break statement|break]] and [[Control flow#Continuation with next iteration|continue]] statements found in C and its derivatives. The break statement causes the innermost loop to be terminated immediately when executed. The continue statement will move at once to the next iteration without further progress through the loop body for the current iteration. A for statement also terminates when a break, goto, or return statement within the statement body is executed.[Wells] Other languages may have similar statements or otherwise provide means to alter the for-loop progress; for example in Fortran 90:

<syntaxhighlight lang="Fortran">
DO I = 1, N
  statements!Executed for all values of "I", up to a disaster if any.
  IF (no good) CYCLE! Skip this value of "I", and continue with the next.
  Statements!Executed only where goodness prevails.
  IF (disaster) EXIT! Abandon the loop.
  Statements!While good and, no disaster.
END DO! Should align with the "DO".
</syntaxhighlight>

Some languages offer further facilities such as naming the various loop constructs so that with multiple nested loops there is no doubt as to which loop is involved. Fortran 90, for example:
<syntaxhighlight lang="Fortran">
X1:DO I = 1, N
     statements
  X2:DO J = 1, M
       statements
       IF (trouble) CYCLE X1
       statements
     END DO X2
     statements
   END DO X1
</syntaxhighlight>
Thus, when "trouble" is detected in the inner loop, the CYCLE X1 (not X2) means that the skip will be to the next iteration for I, ''not'' J. The compiler will also be checking that each END DO has the appropriate label for its position: this is not just a documentation aid. The programmer must still code the problem correctly, but some possible blunders will be blocked.