建立一個循環

Build a Loop is the technique to repeate a sequence of instructions a certain number of times based on an initial and limit value and a specified increment.
It is important to declare all the loop variables.
The generic statement is DO/ index variable, initial value, limit value, increment.

$$ Example of a Do Loop


DECL/INTGR,i

DECL/CHAR,20,elnm

DECL/DOUBLE,xx,yy,zz

$$ This is to create some dummy points.


F(POI_1)=FEAT/POINT,CART, 1.111,2.222,3.333, 0,0,0


F(POI_2)=FEAT/POINT,CART, 4.444,5.555,6.666, 0,0,0


F(POI_3)=FEAT/POINT,CART, 7.777,8.888,9.999, 0,0,0


FA(POI_1)=FEAT/POINT,CART, 1.111,2.222,3.333, 0,0,0


FA(POI_2)=FEAT/POINT,CART, 4.444,5.555,6.666, 0,0,0


FA(POI_3)=FEAT/POINT,CART, 7.777,8.888,9.999, 0,0,0


$$ DO/ index variable, initial value, limit value, increment


DO/i,1,3,1

$$ commands executed during each Do cycle


elnm=ASSIGN/CONCAT('poi_',STR(i))

xx=OBTAIN/FA(@elnm),3

yy=OBTAIN/FA(@elnm),4

zz=OBTAIN/FA(@elnm),5

elnm=ASSIGN/CONCAT('newpoi_',STR(i))

F(@elnm)=FEAT/POINT,CART, xx,yy,zz, 0,0,0

FA(@elnm)=FEAT/POINT,CART, xx,yy,zz, 0,0,0

ENDDO