Thread: C Beginner - Fahrenheit and Celsius Converter

I apologize, I am new to C programming. I know my current program will not compile. Can anyone give me insight into what I can do to fix it? Specifically, how can I store the the start temperature so it can be used again in the final printf statement "start degrees Fahrenheit is converted Celsius."?

Note - I want to use the float data type for precision.

Code:

//THIS PROGRAM WILL CONVERT TEMPERATURES BETWEEN DEGREES FAHRENHEIT AND DEGREES CELSIUS


#include <stdio.h>


int main(void)
{
        //DECLARE VARIABLES
        char x;
        float start_temp, end_temp;


        //DISPLAY TO USER THE PURPOSE OF THE PROGRAM
        printf ("\n\n");
        printf ("This program will convert temperatures between degrees Fahrenheit and degrees Celsius.");
        printf ("\n\n");


        //ASK WHICH SYSTEM USER WOULD LIKE TO CONVERT
        printf ("Would you like to convert from Fahrenheit or Celsius (Enter C or F): ");
        scanf ("%c", &x);
        printf ("\n");


                 //IF FAHRENHEIT; ENTER TEMPERATURE                 
                if (x == 'F' || x == 'f')
                {
                printf ("Enter the temperature in Fahrenheit (F): ");
                scanf ("%f", &start_temp);


                end_temp = (start_temp-32)/1.8;


                //DISPLAY RESULT        
                printf ("%f degrees Fahrenheit is %f Celsius.", start_temp, end_temp);
                }


                //IF CELSIUS; ENTER TEMPERATURE
                else
                {
                printf ("Enter the temperature in Celsius (C): ");
                scanf ("%f", &start_temp);


                end_temp = start_temp * 1.8 + 32;


                //DISPLAY RESULT
                printf ("%f degrees Celsius is %f Fahrenheit.", start_temp, end_temp);
                }


        printf ("\n\n");


        //END PROGRAM


        return 0;
}

You might want to check to see if the input was ok - I noticed that you don't actually check if the input is c/C

Code:

//IF CELSIUS; ENTER TEMPERATURE
else if (x == 'C' || x == 'c')
{
  ...
}
//If user has entered something else
else
{
  puts("\nInvalid key");
}

Also with the scanf("%c"..), because this is your first input, it probably won't matter, but this will probably interest you - FAQ > How do I avoid a "dangling" newline when reading single character user input? - Cprogramming.com - I would personally prefer the function getchar over scanf(" %c"...