how to convert this code into function...

[ballpen1019]

my problem is to convert this code into function....cou ld someone help me to solve these problem..???

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>

main()
{
    int n, N, year, choice = 0;
    float val, value, deprec, tag;
    char answer1 = 'Y', answer2 = 'Y';

    while(toupper(answer1) != 'N')
    {
        system("CLS");

        if(toupper(answer2) != 'N')
        {
            printf("\nOriginal value: ");
            scanf("%f", &value);
            printf("Number of years: ");
            scanf("%d", &N);
        }
        printf("\nMethod: (1-SL 2-DDB 3-SYD) ");
        scanf("%d", &choice);

        val = value;
        n = N;

        switch(choice)
        {
            case 1:
                printf("\nStraight Line Method\n\n");
                deprec = val/n;
                for (year = 1; year <= n; ++year)
                {
                    val -= deprec;
                    printf("End of year %2d ", year);
                    printf("Depreciation: %7.2f ", deprec);
                    printf("Current value:%8.2f\n", val);
                }
                break;
            case 2:
                printf("\nDouble Declining Balance Method\n\n");
                for (year = 1; year <= n; ++year)
                {
                    deprec = 2*val/n;
                    val -= deprec;
                    printf("End of year %2d ", year);
                    printf("Depreciation: %7.2f ", deprec);
                    printf("Current value:%8.2f\n", val);
                }
                break;
            case 3:
                printf("\nSum-of-the-Years\'-Digits method\n\n");
                tag = val;
                for (year = 1; year <= n; ++year)
                {
                    deprec = (n-year+1)*tag/(n*(n+1)/2);
                    val -= deprec;
                    printf("End of year %2d ", year);
                    printf("Depreciation: %7.2f ", deprec);
                    printf("Current value:%8.2f\n", val);
                }
                break;
            default: printf("NOT A VALID CHOICE");
        }
        printf("\n\nAnother calculation? [Y/N] ");
        scanf("%1s", &answer1);
        if(toupper(answer1) != 'N')
        {
            printf("Enter a new set of data? [Y/N] ");
            scanf("%1s", &answer2);
        }

    }
    printf("\nNormal Termination... ");

    system("PAUSE");
}

please help me to solve this problem...,.tha nk you...

[Banfa]

It's already in a function, main(). You need to be more precise about which bit of the code needs to be in a separate function.