A value can be assigned to a substring of a string variable, dynamic array or dimensioned array variable using the three assignment statements described below.
X[start#,replace#] = expression
X{<attr#{,value#{,subvalue#}}>}{[start#, replace#]} = expression
X(row{,column}) {<attr#{,value#{,subvalue#}}>} {[start#,replace#]} = expression
The first form of the statement replaces the substring defined by start# (the first character position) and replace# (the number of characters) with the string given by expression.
The second form replaces a substring of dynamic array X with the string given by expression.
The third form replaces a substring of dimensioned array X with the string given by expression.
Note: The discussion and examples in this section concentrate on simple substring assignment. For more information about array assignment, refer to the description of dynamic arrays.
In the statement
X[start#,replace#] = "ABC"
start# and replace# have the following meanings:
start# > 0 The starting position of the substring counting from the left.
start# = 0 Same as the value start# = 1.
start# < 0 The starting character of the substring counting backward from the right. For instance, -1 is the last character of the string, -2 is second to the last, and so on.
replace# > 0 The number of characters to replace in the substring in X, starting with start# and continuing left to right.
replace# = 0 A substring of zero length is
replaced in X, meaning that the new string ("ABC" in the example) is
inserted, starting at character position start#.
If start# >= 0, the new string is
inserted to the left of start#. If start# < 0, the new string is
inserted to the right of start#. X[1,0] concatenates a string to the front of X
and X[-1,0] concatenates a string to the end of X.
replace# < 0 The last character of the substring, counting from the right side of the string. If replace# is -1, the substring is replaced, from start# to the end of the string, with the expression on the right-hand-side. This makes it easy to manipulate strings of unknown length.
If X = "ABCDEFGH", the following substring values are assigned:
X[-5,-3]="vwxyz"
X becomes ABCvwxyzGH by replacing the substring starting five characters from the end of string X and ending three characters from the end.
X[1,0]="999"
X becomes 999ABCDEFGH by concatenating the subvalue 999 to the front of string X.