Take a look at this program

[abyssphobia]

Well a friend sent me this code and ask me if I can figure out what is wrong, but the proble is I donno C, I barely understood the instructions, its totally different to C++, well if someone knows Ill be glad.

#include<stdio.h> 
#include<conio.h> 
#include<string.h> 

void main() 
{ 
	float tmp,c,k,f;
	int grd;
	printf("\n\r How grade you want?\r 1.-Celcius \n\r 2.-Farenheit \n\r 3.-Kelvin");
	scanf("\n\r %i",&grd);
	scanf("\n\r %f",&tmp);
	if (grd==1)
	{
		f=(tmp*1.8)+32;
		k= tmp+273;
		printf("\n\r Farenheit%f Kelvin%f",&f,&k);
	}
	if (grd==2)
	{
		c= (tmp-32)/1.8;
		k= c+273;
	}
	if (grd==3)
	{
		c= tmp-273;
		f= (c*1.8)+32;

	}
	

	}

[Thantos]

void main()

scanf("\n\r %i",&grd);
scanf("\n\r %f",&tmp);

Fix those three lines and finish off main() [put a return 0; and a closing }] and go from there.

[kermit]

A couple more things

#include<stdio.h> 
#include<conio.h>  /* This is not a standard C header - you don't even need it here */
#include<string.h>

void main()
{ 
	float tmp,c,k,f;
	int grd;
	printf("\n\r How grade you want?\r 1.-Celcius \n\r 2.-Farenheit \n\r 3.-Kelvin"); /* the escape sequence 
'\n' includes the carriage return, so you only need the '\n'*/
	scanf("\n\r %i",&grd); 
	scanf("\n\r %f",&tmp);   /* Also, you don't need the '\n' with scanf */
	if (grd==1)
	{
		f=(tmp*1.8)+32;
		k= tmp+273;
		printf("\n\r Farenheit%f Kelvin%f",&f,&k);  /* You specify a float but pass printf() an address */
	}
	if (grd==2)
	{
		c= (tmp-32)/1.8;
		k= c+273;
	}
	if (grd==3)
	{
		c= tmp-273;
		f= (c*1.8)+32;

	}
	

	}

Also, like Thantos said, its int main(void), not void main(). main() returns an int, therefore its wrong to declare main as returning nothing. It does not matter what your book or your teacher says. If they tell you void main() is correct, then they are wrong. Get a new teacher/book.

When you are using float variables, try putting an f after the number.

c= tmp-273.0f;

The '.0' is a matter of style - some say it makes the intention clearer..

~/

[itsme86]

Here's one way of doing what I think you're trying to do:

itsme@dreams:~/C$ cat temperature.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

enum { TEMP_C = 1, TEMP_F = 2, TEMP_K = 3 };

// To avoid writing 6 functions, convert everything to kelvin first
double deg_to_kelvin(double temp, int scale)
{
  double rv;

  switch(scale)
  {
    case TEMP_C: rv = temp+273;          break;
    case TEMP_F: rv = (temp-32)/1.8+273; break;
    case TEMP_K: rv = temp;              break;
    default:
      puts("Unhandled scale!");
      exit(EXIT_FAILURE);
  }

  return rv;
}

double deg_to_celcius(double temp)
{
  return temp-273;
}

double deg_to_farenheit(double temp)
{
  return (temp-273)*1.8+32;
}

int main(void)
{
  char buf[4096];
  int scale;
  double temp, kelvin_temp;

  do
  {
    printf("Temperature is in:\n  1) Celcius\n  2) Farenheit\n  3) Kelvin\n? ");
    fflush(stdout);
    fgets(buf, sizeof(buf), stdin);
    scale = atoi(buf);
  } while(scale < 1 || scale > 3);

  printf("And the temperature is: ");
  fflush(stdout);
  fgets(buf, sizeof(buf), stdin);
  temp = atof(buf);

  kelvin_temp = deg_to_kelvin(temp, scale);
  printf("\nCelcius  : %.2f\n", deg_to_celcius(kelvin_temp));
  printf("Farenheit: %.2f\n", deg_to_farenheit(kelvin_temp));
  printf("Kelvin   : %.2f\n", kelvin_temp);

  return 0;
}

[abyssphobia]

thank you for all your help!

------------------------abyssphobia--------------------