pic - c18 coding advice / braces error / function declaration help

I have almost NO experience coding so please excuse the crude style and verbose commenting. I am trying to sample from 4 sensors (1 every 15 minutes). I thought it would be more efficient to have the delay and data_write functions as separate functions to call but that's just not working out very well. I consistently get the following error:

Error [1302] old style function declarations not supported

at the end of the data_write function no matter where or how I put the braces (nested, same line, eliminate, etc.) delay function doesn't give the error whether it's before or after the data_write function.

Please feel free to recommend a better layout for me. Also, I really don't have any understanding of the data memory so this routine is probably crap, I know. It's strangely not giving me any errors though so I'll not look that gift horse in the mouth just yet.

=====================================

    #include 
    #include 
    #include 
    #include 
    #include 


    int result;                         // used in ADC result handling
    int i;                              // used in delay loop/function
    int data_adr=0x64;                  // used in data_write function. initial=d100

    // assuming 4MHz oscillator => 8fosc.   Tinst= (4)*Tosc = (4)*(250ns) = 1us
    // all 4 sensors should read every minute so each will begin sequentially,
    // after 15sec delay from previous ADC conversion completes.

    void delay (void);                 // delay function prototype declaration

    void data_write (int, int);             // data-write function prototype declaration

    main()
    {
    // I think I need a while (1) loop here to repeat the loop forever???

    // sensor 1 configured to port AN0
        OpenADC(ADC_FOSC_8 & ADC_RIGHT_JUST & ADC_5ANA_0REF, ADC_CH0 & ADC_INT_OFF);
                            //configures ADC for port AN0 = sensor 1 input
            delay();                    // call the delay function

            ConvertADC();               // initiate conversion of sensor1 @ AN0
            while(BusyADC());           // waiting to complete conversion
            result=ReadADC();           // read the result of sensor1 @ AN0
            data_write();               // call data_write function
        CloseADC();


    // sensor 2 configured to port AN1
        OpenADC(ADC_FOSC_8 & ADC_RIGHT_JUST & ADC_5ANA_0REF, ADC_CH1 & ADC_INT_OFF);
                            //configures ADC for port AN1 = sensor 2 input

           delay();
           ConvertADC();
           while(BusyADC());
           result=ReadADC();
           data_write ();
        CloseADC();

    // sensor 3 configured to port AN2
        OpenADC(ADC_FOSC_8 & ADC_RIGHT_JUST & ADC_5ANA_0REF, ADC_CH2 & ADC_INT_OFF);
                            //configures ADC for port AN2 = sensor 3 input

           delay();
           ConvertADC();
           while(BusyADC());
           result=ReadADC();
           data_write ();
        CloseADC();

    // sensor 4 configured to port AN3
        OpenADC(ADC_FOSC_8 & ADC_RIGHT_JUST & ADC_5ANA_0REF, ADC_CH3 & ADC_INT_OFF);
                            //configures ADC for port AN3 = sensor 4 input

           delay();
           ConvertADC();
           while(BusyADC());
           result=ReadADC();
           data_write ();
        CloseADC();

        return (result);
    }


    // Delay function sequence
    void delay (void)
    {                                       // 15second delay routine
                                    // 15sec/Tinst= 15sec/1us
                                    // = 15*10^6 Tinst = 10K * 1500
                                    // Delay10KTCYx(1)= 0.01sec
                                    // = (10K)*(250)*(6)
        i=6;
        while(i>0) {
           Delay10KTCYx(250);      // 2.5sec delay

            i=i--;                  // run 6 times for total 15sec delay loop
        }
        return;
    }

    // data write sequence
    void data_write (data_adr, result) {
         _asm
         movlw  data_adr        // starting data memory address = data_adr
         movwf  EEADR,A

         movlw  result              // gets data stored in "result" variable
         movwf  EEDATA,A            // places data into data memory holder
         bcf    EECON1,EEPGD,A      // points to data memory
         bcf    EECON1,CFGS,A       // access data eeprom
         bsf    EECON1,WREN,A       // enable write to data EEPROM
         bcf    INTCON,IE,A         // disable interrupt
         movlw  0x55                // start flash erase sequence
         movwf  EECON2,A
         movlw  0xAA
         movwf  EECON2,A            // end flash erase sequence

         bsf    EECONN1,WR,A        // enable bit to start the write operation
         bsf    INTCON,GIE,A        // re-enable interrupt
         bcf    EECON1,WREN         // restores the write command to =disabled
         _endasm

         data_adr = data_adr+2;
         if (data_adr >= 0xC6)      // if address >= d'198
             data_adr = 0x64;       // resets starting point to d'100

        return; }

Answer

All of the other answers have good points, and point out other problems, but the specific reason you're getting the error old style function declarations not supported is because your data_write function declaration is missing the types. It needs to be changed from

void data_write (data_adr, result)

to

void data_write (int data_adr, int result)