compile this !!!!

test0.c

#include<stdio.h>
main()
{
fun(2.3);
}


test1.c

#include<stdio.h>
void fun(float a)
{
printf(" yes it did");
}


compile this :
$gcc test[0-1].c


now replace test1.c


#include<stdio.h>
void fun(float a)
{
printf(" yes it did %f ",a);
}

again compile


??????????

program is compiling well w/o any error but on executing it is giving wrong value of f as passed in function.
Why is it so