Question

So I am trying to write a function that receives a float value, returns a float value, and is displayed in main with printf. I keep getting the same errors:
markup2.c:58: error: conflicting types for ‘GetPrice’
markup2.c:46: error: previous implicit declaration of ‘GetPrice’ was here

Where am I making the mistake? I’ve tried typecasting everything that touches GetPrice but still no luck. Can someone please explain what I am doing wrong?

    #include<stdio.h>

// define the constant MARKUP as float value 0.1
#define MARKUP 0.1

int main()
{
    // declare variables
    char proceed;
    float value;
    float markupValue;

    // display welcome message to user and inform them of markup rate
    printf("\nThank you for using Chad Hammond's markup calculator.\n");
    printf("The current markup rate is %.1f%c.\n",MARKUP*100,'%');

    // ask user if they want to perform a markup
    printf("Would you like to markup an item? y/n:\n");
    scanf("%c", &proceed);

    // if yes, proceed to next step
    if(proceed == 'y')
    {
        // prompt user for the price of item to be marked up
        printf("Please enter a wholesale value to markup: ");
        scanf("%f", &value);

        // display input back to user
        printf("The wholesale value you entered was: %c%.2f\n",'$', value);
        markupValue = (value*MARKUP);

        // display amount of increase
        printf("The dollar amount of this increase will be: %c%.2f\n",'$', markupValue);

        // display total price after increse
        printf("The price for this item after markup is: %c%.2f\n",'$', (float)GetPrice(value));
    }else
        // if user did not want to markup an item, belittle them with sarcasm
        printf("Well, if you didn't want to markup an item you should have just used a Ti-83 and left me alone!\n\n");
    // display exit message
    printf("Thank you for using HammondInstruments Markup Calculator, goodbye.\n");

    // return that program has completed
    return 0;
}

float GetPrice(float value)
{
    float output;
    value += value*MARKUP;
    output = value;
    return (float)output;
}

Answer 1

You will need to either declare or define GetPrice before your main.