Thread: Loop issue in tax program

Below is my code. The problem is the program does compile and run, but it is not right. When u enter a numeric value it gives u the tax for all 3 locations; however, when you enter a letter or letters it lets u loop back to re enter a correct number and it will loop back several times if u continue to enter letters instead of numbers. The problem is if after u enter letters and it loops back, if you enter a number the program still thinks its an invalid entry. So what am i doing wrong. Please exlain to me what i am doing wrong so I can fix this issue, thanks.

Code:

#include <stdio.h> // Include standard I/O libraries
#include <stdlib.h> // Include standard libraries
#include <math.h> // Include Math libraries

/* Defining tax rates for Kudler's three store */
    float DelMarRate = 7.25;    /* Del Mar tax rate */
    float EncinitasRate = 7.5;    /* Encintas tax rate */
    float LaJollaRate = 7.75;    /* LaJolla tax rate */
    
/* Variables for Kudler's three store's tax calculation */   
    float DelMarTax = 0.0;        /* Calculation variable for Del Mar taxes */
    float EncinitasTax = 0.0;      /* Calculation variable for Encintas taxes */
    float LaJollaTax = 0.0;       /* Calculation variable for LaJolla taxes */
    float Amount = 0.0;

int main(void)
{
char Purchase[32]; /* Declare variables */

int i,Return=0; 

    /* Prompt user for Purchase Amount */
    printf("\n*********************************");
    printf("\n* Welcome to Kudler Fine foods! *");
    printf("\n*********************************");
    printf("\n\n");
    printf("\n\nPlease Enter the customer's purchase amount:$");
    scanf("%s", Purchase);

do{
        /* Loop - Test the numeric values*/ 
        for(i=0; Purchase[i]; i++) 
        {
            if(Purchase[i] < '0' || Purchase[i] > '9') /* Test for a numeric value (0-9) */
            {
            if (Purchase[i] == '.') /* If character is a decimal continue */
            continue;
                else
                Return=1; /* Set Non-Numerical Value flag */
                break; 
            } 
        }

            if (Return == 1) /* If Non-Numerical Value print Error Message and allow user to re-enter purchase price */
            {
                printf("\n\nError! Invalid Purchase Amount [ %s ]\n",Purchase);
                fflush(stdin);
                printf("\n\nPlease Re-enter Purchase Amount:$"); 
                scanf("%s", Purchase); 
                
            } 
                             
}while (Return == 1);

Amount=atof(Purchase); /* Convert to Float */ 
DelMarTax=(Amount*DelMarRate)/100; /* Calculate Tax Amount for Del Mar */
EncinitasTax=(Amount*EncinitasRate)/100; /* Calculate Tax Amount for Encinitas */
LaJollaTax=(Amount*LaJollaRate)/100; /* Calculate Tax Amount for La Jolla */

    /* Display Tax Calculation output to the screen */
    printf("\n\n\n");
    printf("Del Mar\t\tEncinitas\tLa Jolla\t\n");
    printf("*******************************************\n");
    printf("$%.2f\t\t$%.2f\t\t$%.2f\n", DelMarTax, EncinitasTax, LaJollaTax);
    printf("\n\nPlease Press The Enter Key To Exit Program!\n\n");
    fflush(stdin);
    
    /*Keeping DOS Screen open so user can view output*/
        scanf("%c\n");    
    
        return 0;
    
}

Okay, which scanf(). The one under the re-enter purchase amount? and how do i clear the input buffer when an incorrect value is entered? Thanks.

I would do both so that it doesn't matter where the user screws up.

And the FAQ will tell you the rest; look at the top of our page.

Thanks the program works beautifully i forgot to add a return = 0; after the do statement. I figured it out on my own.

ONE NOTE: IF ANYONE READS THIS FORUM AND IS IN CSS 561 PLZ DO NOT COPY MY CODE AS THE POSTED CODE IS MY ORIGINAL WORK. IF THE CODE IS COPIED AND I AM CONTACTED BY THE INSTRUCTOR I WILL SHOW THIS THREAD TO MY INSTRUCTOR.

Amanda Smith