millfork/examples/c64/calculator.mfk

import stdio
import c64_basic

void main() {
    word a
    word b

    putstrz("enter first number:{n}"z)
    a = readword()
    while readword_err != 0 {
        putstrz("that wasn't a number, try again:{n}"z)
        a = readword()
    }

    putstrz("enter second number:{n}"z)
    b = readword()
    while readword_err != 0 {
        putstrz("that wasn't a number, try again:{n}"z)
        b = readword()
    }

    putstrz("the sum is:{n}"z)
    a += b
    putword(a)
    putchar(13)
}