millfork/examples/crossplatform/calculator.mfk

import stdio

#if CBM_64
    import c64_basic
#elseif CBM_264
    import c264_basic
#elseif ZX_SPECTRUM || NEC_PC_88
    // no imports needed
#else
    #error Unsupported platform
#endif

void main() {
    word a
    word b

    putstrz("enter first number:"z)
    new_line()
    a = readword()
    while errno != err_ok {
        putstrz("that wasn't a number, try again:"z)
        new_line()
        a = readword()
    }

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

    putstrz("the sum is:"z)
    new_line()
    putword(a + b)
    new_line()
}