Listing 2 Illustrates automatic conversion via function prototypes

/* convert2.c */
#include <stdio.h>

void dprint(double);

main()
{
   dprint(123);
   dprint(123.0);
   return 0;
}

void dprint(double d)
{
   printf("%f\n",d);
}

/* Output:
123.000000
123.000000
*/

/* End of File */