RosettaCodeData/Task/Rep-string/Forth/rep-string-1.fth

22 lines
575 B
Forth

: rep-string ( caddr1 u1 -- caddr2 u2 ) \ u2=0: not a rep-string
2dup dup >r r@ 2/ /string
begin 2over 2over string-prefix? 0= over r@ < and while -1 /string repeat
r> swap - >r 2drop r> ;
: test ( caddr u -- )
2dup type ." has "
rep-string ?dup 0= if drop ." no " else type ." as " then
." repeating substring" cr ;
: tests
s" 1001110011" test
s" 1110111011" test
s" 0010010010" test
s" 1010101010" test
s" 1111111111" test
s" 0100101101" test
s" 0100100" test
s" 101" test
s" 11" test
s" 00" test
s" 1" test ;