Copy one string into another, ignoring trailing blanks chrAppnd
"str1" (or as much of it as there is room for) is copied into the part of "str2" beginning at
position "iposn". "iposn" is updated to indicate the final length of "str2" after this
operation. Trailing blanks in "str1" are ignored. "iposn" will be set to the total length of "str2" (excluding the trailing null). ’ str2’ string. This should include room for the terminating null. "str2". If "str2" is empty on entry, then this should be supplied as zero. On exit,
the supplied value is incremented by the length of "str1" (ignoring any trailing spaces).