The most basic way to alter the contents of an existing string is with
aset (see Array Functions).
) stores char into string at index
idx. Each character occupies one or more bytes, and if char
needs a different number of bytes from the character already present at
aset signals an error.
A more powerful function is
This function alters part of the contents of the string string, by storing obj starting at index idx. The argument obj may be either a character or a (smaller) string.
Since it is impossible to change the length of an existing string, it is an error if obj doesn't fit within string's actual length, or if any new character requires a different number of bytes from the character currently present at that point in string.
To clear out a string that contained a password, use