String-Alter!

(string-alter! string1 integer1 integer2 string2) -> null

Using the Indexing System: a portion of String1, from index indicated by Integer1 for a length indicated by Integer2, is replaced with String2.

>> (define a "a cdefgh")
:: "a cdefgh"
>> (string-alter! a 1 1 "b")
:: null
>> a
:: "abcdefgh"
>> (string-alter! a 1 5 "BCD")
:: null
>> a
:: "aBCDgh"