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Welcome to the Fibonacci in Algol68 page! Here, you'll find the source code for this program as well as a description of how the program works.
MODE PARSEINT_RESULT = STRUCT(BOOL valid, INT value, STRING leftover); MODE PARSEINTLIST_RESULT = STRUCT(BOOL valid, REF INT values); PROC parse int = (REF STRING s) PARSEINT_RESULT: ( BOOL valid := FALSE; REAL r := 0.0; INT n := 0; STRING leftover; # Associate string with a file # FILE f; associate(f, s); # On end of input, exit if valid number not seen. Otherwise ignore it # on logical file end(f, (REF FILE dummy) BOOL: ( IF NOT valid THEN done FI; TRUE ) ); # Exit if value error # on value error(f, (REF FILE dummy) BOOL: done); # Convert string to real number # get(f, r); # If real number is in range of an integer, convert to integer. Indicate integer is valid if same as real # IF ABS r <= max int THEN n := ENTIER(r); valid := (n = r) FI; # Get leftover string # get(f, leftover); done: close(f); PARSEINT_RESULT(valid, n, leftover) ); PROC usage = VOID: printf(($gl$, "Usage: please input the count of fibonacci numbers to output")); COMMENT fib(n) = fib(n - 1) + fib(n - 2) where: - fib(0) = 0 - fib(1) = 1 COMMENT MODE FIBSTATE = STRUCT(INT prev, INT result); PROC init fib = FIBSTATE: FIBSTATE(0, 1); OP FIB = (FIBSTATE state) FIBSTATE: (result OF state, prev OF state + result OF state); OP FIBRESULT = (FIBSTATE state) INT: prev OF state; PROC show fibonacci values = (INT n) VOID: ( # Initialize Fibonacci state # FIBSTATE state := init fib; # Update Fibonacci state and show results for requested number of values # FOR k TO n DO state := FIB state; printf(($g": "gl$, whole(k, 0), whole(FIBRESULT state, 0))) OD ); # Parse 1st command-line argument # STRING s := argv(4); PARSEINT_RESULT result := parse int(s); # If invalid or extra characters, exit # INT n := value OF result; IF NOT (valid OF result) OR (leftover OF result) /= "" THEN usage; stop FI; # Show requested number of Fibonacci values # show fibonacci values(n)
Fibonacci in Algol68 was written by:
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Note: The solution shown above is the current solution in the Sample Programs repository as of Jan 31 2023 21:23:22. The solution was first committed on Jan 21 2023 16:11:14. As a result, documentation below may be outdated.
No 'How to Implement the Solution' section available. Please consider contributing.
No 'How to Run the Solution' section available. Please consider contributing.