why this code not work ??

```
# include <stdio.h>
void get_values(float *r, float *v);
float do_calculations(float resistance, float voltage ) ;
void display_answer(float current);
main()
{
float resistor;
float volts;
float current;
//explain_program();
get_values(*r, *v);
current = do_calculations(resistor, volts);
display_answer(current);
}
void explain_program()
{
printf("This program calculates the current in amps. \n");
printf("Please enter the value of R in ohms and v in volts .\n");
}
void get_values(float *r, float *v)
{
float resistance;
printf("\n\n Input the resistance in ohms = ");
scanf("%f", &*r); // scan resistance
printf("Input the voltage in volts ="); // scan volts
scanf("%f", &*v);
//*r = resistance;
}
float do_calculations(float resistance, float voltage)
{
float current;
current = voltage / resistance;
return (current);
}
void display_answer(float current)
{
printf("the value of current is %f amps ", current);
}
```