New programmer - please help!

I've only just started a course in C Programming, and I've never done any programming before. My exercise asks me to write a program that converts litres into pints and fluid ounces. I have written what I thought was correct, but when running the program it just gives an output of zero for both pints and fluid ounces. The code is:

Code:

---

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int main (void)
{
    const litres2floz=35.1950652;
    float a;    //litres
    float b=a*litres2floz;    //fluid ounces
    int c=(b/20);  //pints


    printf("Enter the number of litres\n");
    scanf("%f",&a);

    printf("%f litres = %d pints and %f fluid ounces\n",a,c,b-(c*20));

    system("pause");
    return 0;


 }

---

If anyone can see where I have gone wrong in this it would be a big help.

Thanks guys.

Does your compiler not emit any errors or warnings? What type, exactly, do you think the variable litres2floz is? What value is the variable, a initially? What value, therefore, does the variable, b, take?

When compiled the compiler tells me that there are no errors in the code. It just doesn't do the conversions.

With regards to a haven't I defined it so that I can enter a value for it and all other values will change correspondingly?

Then you should turn up the warnings level on your compiler.

const litres2floz doesn't specify a type for the variable litres2floz, only that it is constant. What type (int, float, double char etc) do you expect it to be?

Place a printf statement after you have declared all your variables(litres2floz, a,b and c) to display what each is. Do they take the values you expect them to?

The only value that takes the one I expect it to is a. The others just display themselves as 0.

Any idea how I go about changing the warnings level on Dev C++?

Project menu --> project options, select the 'parameters' tab and enter -Wall in the 'compiler' field.

Code:

---

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

int main (void)
{
    const float litres2pints=1.76;
    const float pints2floz=20;
    float a;
    float b;
    int c;
    float d;


    printf("Enter the number of litres\n");
    scanf("%f",&a);
    b=a*litres2pints;
    c = (int)b;
    d=(b-c)*pints2floz;

    printf("%f litres = %d pints and %f fluid ounces\n",a,c,d);

    system("pause");
    return 0;


 }

---

This seems to work. Does it look correct to you?

There's a lot of weird stuff in your code.

Here's what I picked up :

Code:

---

const litres2floz=35.1950652;

---

Well, as specified before....

Code:

---

float a;    //litres
float b=a*litres2floz;    //fluid ounces
int c=(b/20);  //pints

---

Since, a is not given a value, who knows what value b is going to end up getting. And since you'll have no clue what b will be getting, how would you know what value c is getting ? Further, by divding b (a float), by 20, you'll get a float, and upcasting it to an integer may result in precision errors.

Code:

---

system("pause");

---

The system command is very OS specific. If you ever intend to write portable code, learn to avoid it all together.

For the system("pause"): http://faq.cprogramming.com/cgi-bin/...&id=1043284385

You also don't need <math.h>.