I am very new to OCaml and am attempting to learn and write a program at the same time. I am writing a palindrome program. I am attempting to get a string from the user such as d e v e d or Hello World! or loud all of the preceding are valid user input. I need to read these strings and display them then reverse them and check if it is a palindrome or not. I did the following code...
print_string "Enter a string: ";
let str = read_line () in
Printf.printf "%s\n" str;;
Printf.printf "%s\n" str;;
this works fine and will give the print, Enter a string: d e v e d or Enter a string: Hello World! The issue comes when I try to add another Printf.printf "%s\n" str;; into the code. it gives me an error of File "main.ml", line 5, characters 21-24:
Error: Unbound value str with line 5 being the line of the 2nd Printf.printf statement. I have tried this with no ; for both of the print statements, with 1 or with 2 and I get the same error each time. Does anyone with more OCaml knowledge know why I get this error.
Because of your use of in your code parses as:
(let str = read_line () in Printf.printf "%s\n" str);;
and then a completely separate:
Printf.printf "%s\n" str;;
So str is local to the first printf.
You want:
let str = read_line ();;
Printf.printf "%s\n" str;;
Printf.printf "%s\n" str;;
which is three separate definitions. The first defines a global variable str.