A-M baby

Task/Loops-While/Fortran/loops-while-2.f

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+      PROGRAM LOOPWHILE
+        INTEGER I
+
+C       FORTRAN 77 does not have a while loop, so we use GOTO statements
+C       with conditions instead. This is one of two easy ways to do it.
+        I = 1024
+   10   CONTINUE
+C       Check condition.
+        IF (I .GT. 0) THEN
+C         Handle I.
+          WRITE (*,*) I
+          I = I / 2
+C         Jump back to before the IF block.
+          GOTO 10
+        ENDIF
+
+C       This is an alternative while loop with labels on both ends. This
+C       will use the condition as a break rather than create an entire
+C       IF block. Which you use is up to you, but be aware that you must
+C       use this one if you plan on allowing for breaks.
+        I = 1024
+   20   CONTINUE
+C         If condition is false, break.
+          IF (I .LE. 0) GOTO 30
+C         Handle I.
+          WRITE (*,*) I
+          I = I / 2
+C         Jump back to the "loop" beginning.
+          GOTO 20
+   30   CONTINUE
+
+        STOP
+      END