Adding 2 functions to a C Program

Question

Hello,

   I need to add two functions to this C Program here: https://onlinegdb.com/uqjIhF5AH

I am trying to do it, but can't get it to work. I want to add the following functions:

int main()
{
    float celsius, fahrenheit;
 
    printf("Please Enter the temperature in Fahrenheit: \n");
    scanf("%f", &fahrenheit);
 
    // Convert the temperature from f to c formula
    celsius = (fahrenheit - 32) * 5 / 9;
    //celsius = 5 *(fahrenheit - 32) / 9;
    //celsius =(fahrenheit-32) * 0.55556;

printf("\n %.2f Fahrenheit = %.2f Celsius", fahrenheit, celsius);
 
    return 0;
}

2nd Function:

int main()
{
  printf("\n Hello World");
  return 0;
}

Thank you for the help.

Jon

Answer 1

You cannot have more than one main() function (actually, you cannot have more than 1 function with the same name) in a C program.

The main() function is the entry point of your application. Create new functions and put the functionality there. E.g.:

int MyFunction1()
{
    ...
    return 42;
}

void MyFunction2(int value)
{
    ...
}

int main()
{
    int number = MyFunction1();
    MyFunction2(number);
    return 0;
}

Answer 2

/* C Program to Calculate Square, Square root, Triangle Perimeter and Grade Average */

#include<stdio.h>

#include<math.h>

int Calculate_Square (int Number);

float Calculate_Perimeter_Triangle (float a, float b, float c);

float Calculate_Grade (float grade1, float grade2, float grade3,

       float grade4);

int

main ()

{

  int number, Square;

  float a, b, c, Triangle, Square_Root;

  float grade1, grade2, grade3, grade4, Grade;

  printf (" \n Please Enter any integer Value : ");

  scanf ("%d", &number);

  Square = Calculate_Square (number);

  printf ("\n Square of a given number %d = %d\n", number, Square);

/* Square Root */

  printf ("The square root of your number %d is %f\n", number, sqrt (number));

  printf ("\nPlease Enter three sides of triangle\n");

  scanf ("%f%f%f", &a, &b, &c);

  printf ("Enter 4 grade values for your course:\n");

  scanf ("%f%f%f%f", &grade1, &grade2, &grade3, &grade4);

  Grade = Calculate_Grade (grade1, grade2, grade3, grade4);

  printf ("Your grade average is %f\n", Grade);

/* Triangle */

  Triangle = Calculate_Perimeter_Triangle (a, b, c);

  printf ("Area of triangle is %f\n", Triangle);

  return 0;

}

int

Calculate_Square (int Number)

{

  return Number * Number;

}

float

Calculate_Perimeter_Triangle (float a, float b, float c)

{

  float s, Perimeter;

  Perimeter = a + b + c;

  return Perimeter;

}

float

Calculate_Grade (float g1, float g2, float g3, float g4){

}

Answer 3

Just rename your main() to Main() and _main() and add these to your program and call them accordingly. In C, function names are case sensitive and therefore main and Main would be different, since in C you can use only one main function.