//title:pkc-ver256.c

/* Fahrenheit to Celsius or Celsius to Fahrenheit conversion program, Revision 5 */
  
#include <stdio.h>     /*Define data type*/
int ask(); //function ask prototype
int calc1(); //function calc1 prototype
int calc2(); //function calc2 prototype
char display(); //function display prototype

int main()
{
    float fFahrenheit = 0.0f;     /*Variable to hold Fahrenheit as float*/
    float fCelsius = 0.0f;    //Variable to hold Celsius as float
    char cAnswer = '\0';         /*Variable to hold yes/no answer*/

    // Ask will be responsible for asking and returning their choice.
    // We store the choice to evaluate in the switch.
    int getit = ask();

    // Using a switch we evaluate what choice they made.
    // 1, 2 and any other input is considered exit.

    switch (getit) {
        case 1:
            calc1();
            break;
        case 2:
            calc2();
            break;
        default:
            // Exits on any choice besides 1 and 2
            break;
    }

    return 0;
}
int ask()
{
    int choice=0;

    // Prompt for choice
    printf("Enter 1 to convert a Fahrenheit temperature to Celsius\n");
    printf("Enter 2 to convert a Celsius temperature to Fahrenheit\n");
    printf("Enter 3 to exit\n");
    scanf("%d",&choice);

    // Check if the number they chose is one of the 3 and is a digit
    if  ((isdigit(choice)) && (choice < 1) || (choice > 3)) {
        printf("Sorry, you must choose 1, 2, or 3. Please try again.\n");
        scanf("%d",&choice);
    }  //end if
    else {
    
    // Return that choice to main
    return choice;
}    // end else    
}    // end ask

// Again we match the prototype.
// Since we are void, we don't return anything. We just collect, calculate, and print message.

int calc1()
{
    float fFahrenheit = 0.0f;         /*Variable to hold Fahrenheit as float*/
    float fCelsius = 0.0f;        //Variable to hold Celsius as float
    int choice=0;         /*Variable to hold answer*/
    printf("Please enter a Faherinheit temperature to be converted to Celsius\n example 82 or 71.5\n");
    scanf("%f",&fFahrenheit); /*Get Fahrenheit variable from user input*/
    fCelsius = (float)(fFahrenheit - 32)/1.8;
    printf("Fahrenheit = %.1f\nCelsius = %.1f\n" , fFahrenheit, fCelsius); /*Print out Fahrenheit number given and the Celsius Equivilant*/
    printf("press 1 to enter another fahrenheit number, 2 for Celsius, or 3 to exit/n");
    scanf("%d",&choice);
     // Check if the number they chose is one of the 3 and is a digit
    while ((isdigit(choice)) && (choice < 1) || (choice > 3)) {
        printf("Sorry, you must choose 1, 2, or 3. Please try again.\n");
        scanf("%d",&choice);
          
    }

    // Return that choice to main
    return choice;
               }

// Prints a message showing our conversion.
int calc2()
{
    float fFahrenheit = 0.0f;         /*Variable to hold Fahrenheit*/
    float fCelsius = 0.0f;        //variable to hold Celsius as float
    char cAnswer = '\0';         /*Variable to hold yes/no answer*/
    printf("Please enter a Celsius temperature to be converted to Fahrenheit\n example 10 or 21.5\n");
    scanf("%f",&fCelsius);   /*Get Celsius variable from user input*/
    fFahrenheit = (float)(fCelsius * 1.8) + 32;
    printf("Fahrenheit = %.1f\nCelsius = %.1f\n" , fFahrenheit, fCelsius); /*Print out Fahrenheit number given and the Celsius Equivilant*/
    printf("Would you like to enter another temperature?  enter y for yes or n for no/n");
    scanf("%c",&cAnswer);
    toupper(cAnswer);
    if (cAnswer=='Y') {
    printf("Please enter a Faherinheit temperature to be converted to Celsius\n example 82 or 71.5\n");
    scanf("%f",&fFahrenheit); /*Get Fahrenheit variable from user input*/
        fCelsius = (fFahrenheit - 32) * (005.00/009.00);  /*Perform calculation to convert fahrenheit to Celsius*/
    printf("Fahrenheit = %.1f\nCelsius = %.1f\n" , fFahrenheit, fCelsius); /*Print out Fahrenheit number given and the Celsius Equivilant*/
    printf("Press enter to exit");
    getchar();
    }    
else    {
    printf("Press enter to exit");
    getchar();
    return 0;}
}  
    
  

int getit = ask();

int getit = 0;
getit = ask();
printf("Value : %d\n",getit);

tom@midnight:/tmp$ cc -o ah ah.c -Wall -Werror -pedantic-errors
ah.c:1:1: error: C++ style comments are not allowed in ISO C90
ah.c:1:1: error: (this will be reported only once per input file)
cc1: warnings being treated as errors
ah.c: In function ‘main’:
ah.c:15: warning: unused variable ‘cAnswer’
ah.c:14: warning: unused variable ‘fCelsius’
ah.c:13: warning: unused variable ‘fFahrenheit’
ah.c: In function ‘ask’:
ah.c:49: warning: implicit declaration of function ‘isdigit’
ah.c:49: warning: suggest parentheses around && within ||
ah.c:58: warning: control reaches end of non-void function
ah.c: In function ‘calc1’:
ah.c:75: warning: suggest parentheses around && within ||
ah.c: In function ‘calc2’:
ah.c:97: warning: implicit declaration of function ‘toupper’
ah.c:97: warning: statement with no effect
ah.c:110: warning: control reaches end of non-void function

void foo(); // Returns 'void'.
int foo(); // Returns an 'int'.

// And so on....