Change temperature F to C is having issues - c

Question

I'm just started learning C programming. So I have problem with change temperature via Functions. Please check this program and where did I do mistake? Thank you!!!
#include<stdio.h>
double f_to_c(double f);
double get_integer(void);
int main(void)
{
double a;
a = get_integer();
printf("he degree in C:%f", f_to_c(a));
return 0;
}
double get_integer(void)
{
double n;
printf("Enter the variable:");
scanf_s("%f", &n);
return n;
}
double f_to_c(double f)
{
int f, c;
c = 5.0 / 0.9*(f - 32.0);
return c;
}
`

Answer 1

In your case,
double f_to_c(double f)
{
int f, c;
c = 5.0 / 0.9*(f - 32.0);
return c;
}
int f is shadowing the double f. Use some other name for the variable(s).
Essentially, you're trying to make use of an uninitialized automatic local variable which invokes undefined behavior

Answer 2

Corrected code below:
#include<stdio.h>
double f_to_c(double f);
double get_integer(void);
int main(void)
{
double a;
a = get_integer();
printf("he degree in C:%lf\n", f_to_c(a));
return 0;
}
double get_integer(void)
{
double n;
printf("Enter the variable:");
scanf("%lf", &n);
return n;
}
double f_to_c(double f)
{
double c;
c = 5.0/9*(f-32);
return c;
}
As you can see:
Type of c variable in f_to_c is changed to double, because of you need a double return for that function
Formula to convert F to C was not correct.
Format specifier of your printf and scanf was not correct.

Answer 3

in get_integer function return type is double, instead it should be integer
int get_integer(void)
{
int n;
printf("Enter the variable:");
scanf_s("%d", &n);
return n;
}
in your other function f_to_c, return type is double but you're returning an integer
double f_to_c(double f)
{
int f;
double c;
c = (5.0 / 0.9)*(f - 32.0);
return c;
}
also at the start, you need to change your code to:
int main(void)
{
int a;
a = get_integer();
printf("he degree in C:%f", f_to_c(a));
return 0;
}