tax calucaltion functions c++

Question

am a beginner programmer and I was to ask a program which calculates income tax based on a salary. Then to change thecode and create below functions however I have no idea how to create them. these are:

float calculate_tax(float amount, float tax_rate);
float calculate_netpay(float amount, float tax);
float increment_salary(float amount, float increment_rate)
.Also I am trying to loop the program so once you enter y or n to continue the program will either calculate again or stop however when I use do while function program does not stop and it calculates all the time so it kind of does not recognize false argument.See below code I created in Visio: Any suggestions would be appreciated.

the code is below:

include<stdio.h>

include<conio.h>

int main()

{
    int employeeID = 0;
    float salary = 0;
    float taxtotal = 0;
    float netpaytotal = 0;
    char c = '-';
    char d[] = "Employee_Payroll";
    int j, k;
    char grade = 0;
    double inc1 = 0.025;
    double inc2 = 0.015;
    double inc3 = 0;
    double Y1tax;
    double Y2tax;
    double Y3tax;
    double Y4tax;
    double Y5tax;
    double netpay;
    double newpay;
    double newpay1;
    double newpay2;
    double newpay3;
    double newpay4;
    char inputChar = 'y';

    do
    {
        printf("Enter Employee ID: ");
        scanf_s("%d", &employeeID);

        printf("\n");

        if (employeeID == 1)

        {
            printf("Enter Salary: ");
            scanf_s("%f", &salary);
        }
        else

        {
            printf("Wrong Employee ID\n");
            exit(0);
        }


        printf("\n");

        if (salary >= 12000 && salary <= 15000)
        {
            for (j = 1; j <= 1; j++)
            {
                for (k = 1; k <= 34; k++)
                {
                    printf("%c", c);
                }
                printf("\n");
                {
                    printf("-------Employee Payroll-----------\n");
                }
            }
            printf("\n");


            printf("Employee ID: %d\n", employeeID);
            printf("Gross Salary: %f\n", salary);
            taxtotal = salary * 0.25;
            printf("Tax: %f\n", taxtotal);

            netpaytotal = salary - taxtotal;
            printf("Net Pay: %f\n", netpaytotal);
        }
        else
        {
            printf("Error: Salary %f is out of range!!!\n", salary);
            exit(0);
        }

        printf("\n");


        if (salary >= 12000 && salary <= 15000 && employeeID == 1)

            for (j = 1; j <= 1; j++)
            {
                for (k = 1; k <= 34; k++)
                {
                    printf("%c", c);
                }
            }

        printf("\n");

        {
            printf("Enter Grade: %c", grade);
            "\n";
            scanf_s(" %c", &grade, 1);
        }
        printf("\n");

        switch (grade)

        {
        case 'A':
            printf("The increment is: %f\n", inc1);
            printf("Increment and tax over the five years\n");

            newpay = (salary * 0.025) + salary;

            Y1tax = newpay * 0.25;
            netpay = newpay - Y1tax;

            printf("Year 1: tax = %f, net pay = %f\n", Y1tax, netpay);

            newpay1 = (newpay * 0.025) + newpay;
            Y2tax = newpay1 * 0.25;
            netpay = newpay1 - Y2tax;

            printf("Year 2: tax = %f, net pay = %f\n", Y2tax, netpay);


            newpay2 = (newpay1 * 0.025) + newpay1;
            Y3tax = newpay2 * 0.25;
            netpay = newpay2 - Y3tax;

            printf("Year 3: tax = %f, net pay = %f\n", Y3tax, netpay);

            newpay3 = (newpay2 * 0.025) + newpay2;
            Y4tax = newpay3 * 0.25;
            netpay = newpay3 - Y4tax;

            printf("Year 4: tax = %f, net pay = %f\n", Y4tax, netpay);

            newpay4 = (newpay3 * 0.025) + newpay3;
            Y5tax = newpay4 * 0.25;
            netpay = newpay4 - Y5tax;

            printf("Year 5: tax = %f, net pay = %f\n", Y5tax, netpay);
            break;

        case 'B':
            printf("The increment is: %f\n", inc2);
            printf("Increment and tax over the five years\n");

            newpay = (salary * 0.015) + salary;

            Y1tax = newpay * 0.25;
            netpay = newpay - Y1tax;

            printf("Year 1: tax = %f, net pay = %f\n", Y1tax, netpay);

            newpay1 = (newpay * 0.015) + newpay;
            Y2tax = newpay1 * 0.25;
            netpay = newpay1 - Y2tax;

            printf("Year 2: tax = %f, net pay = %f\n", Y2tax, netpay);


            newpay2 = (newpay1 * 0.015) + newpay1;
            Y3tax = newpay2 * 0.25;
            netpay = newpay2 - Y3tax;

            printf("Year 3: tax = %f, net pay = %f\n", Y3tax, netpay);

            newpay3 = (newpay2 * 0.015) + newpay2;
            Y4tax = newpay3 * 0.25;
            netpay = newpay3 - Y4tax;

            printf("Year 4: tax = %f, net pay = %f\n", Y4tax, netpay);

            newpay4 = (newpay3 * 0.015) + newpay3;
            Y5tax = newpay4 * 0.25;
            netpay = newpay4 - Y5tax;

            printf("Year 5: tax = %f, net pay = %f\n", Y5tax, netpay);
            break;

        case 'C':
            printf("The increment is: %f\n", inc3);
            printf("Increment and tax over the five years\n");

            int i = 1;
            while (i <= 5)
            {
                printf("Year %d: tax = %f, net pay = %f\n", i, taxtotal, netpaytotal);
                i = i + 1;
            }

        default: printf("Invalid grade\n");
        }
        char inputChar;
        printf("Do you want to continue (y/n)?: ");
        inputChar = _getch();
        printf("%c\n", inputChar);
        while ((inputChar != 'Y' && inputChar != 'y') && (inputChar != 'N' && inputChar != 'n'))
        {
            printf("Please enter y or n: ");
            inputChar = _getch();
            printf("%c\n", inputChar);
        }

    } 


while (inputChar == 'y');
if (inputChar == 'n');
system("pause");

}

Answer 1

 // function declare
 float calculate_tax(float amount, float tax_rate);
 float calculate_netpay(float amount, float tax);
 float increment_salary(float amount, float increment_rate);

 // main
 int main()
 {
 // ......
     char inputChar = 'y';
     do
     {
 // ......  
         // char inputChar; /* Remove this line ...*/
         printf("Do you want to continue (y/n)?: ");
         inputChar = _getch();
         printf("%c\n", inputChar);
         while ((inputChar != 'Y' && inputChar != 'y') && (inputChar != 'N' && inputChar != 'n'))
         {
             printf("Please enter y or n: ");
             inputChar = _getch();
             printf("%c\n", inputChar);
         }
     }
     while (inputChar == 'y');

     if (inputChar == 'n');
     system("pause");

     return 0;
 }

 // function body
 float calculate_tax(float amount, float tax_rate)
 {
    float salary;
    float tax = 0.25;

    return (salary * tax);
 }
 float calculate_netpay(float amount, float tax)
 {
     // Some code
     return 0.0f;
 }
 float increment_salary(float amount, float increment_rate)
 {
     // Some code
     return 0.0f;
 }

Answer 2

You just remove a line (191)... see below

// function declare
float calculate_tax(float amount, float tax_rate);
float calculate_netpay(float amount, float tax);
float increment_salary(float amount, float increment_rate);

// main
int main()
{
// ......
    char inputChar = 'y';
    do
    {
// ......  
        // char inputChar; /* Remove this line ...*/
        printf("Do you want to continue (y/n)?: ");
        inputChar = _getch();
        printf("%c\n", inputChar);
        while ((inputChar != 'Y' && inputChar != 'y') && (inputChar != 'N' && inputChar != 'n'))
        {
            printf("Please enter y or n: ");
            inputChar = _getch();
            printf("%c\n", inputChar);
        }
    }
    while (inputChar == 'y');

    if (inputChar == 'n');
    system("pause");

    return 0;
}

// function body
float calculate_tax(float amount, float tax_rate)
{
    // Some code
    return 0.0f;
}
float calculate_netpay(float amount, float tax)
{
    // Some code
    return 0.0f;
}
float increment_salary(float amount, float increment_rate)
{
    // Some code
    return 0.0f;
}

Answer 3

Hi @Petrus 【KIM】 ,

thank you very much for your reply. y/n works fine now!

However I am still not sure what code I can put when you say 'some code'. Could you please explain?