%SUBST Used as the Result of an Assignment

When used as the result of an assignment this built-in function refers to certain positions of the argument string. Unindexed arrays are not allowed for start and length.

The result begins at the specified starting position in the variable and continues for the length specified. If the length is not specified then the string is referenced to its end. If the length refers to characters beyond the end of the string, then a run-time error is issued.

When %SUBST is used as the result of an assignment, the first parameter must refer to a storage location. That is, the first parameter of the %SUBST operation must be one of the following.

Field
Data Structure
Data Structure Subfield
Array Name
Array Element
Table Element

Any valid expressions are permitted for the second and third parameters of %SUBST when it appears as the result of an assignment with an EVAL operation.

Figure 258. %SUBST Example

CL0N01Factor1+++++++Opcode(E)+Extended-factor2+++++++++++++++++++++++++++
 *
 * In this example, CITY contains 'Toronto, Ontario'
 * %SUBST returns the value 'Ontario'.
 *
C     ' '           SCAN      CITY          C
C                   IF        %SUBST(CITY:C+1) = 'Ontario'
C                   EVAL      CITYCNT = CITYCNT+1
C                   ENDIF
 *
 * Before the EVAL, A has the value 'abcdefghijklmno'.
 * After the EVAL A has the value 'ab****ghijklmno'
 *
C                   EVAL      %SUBST(A:3:4) = '****'

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