basics in using function

hi i tried a small program using function which is as follows

#include<stdio.h>
#include<conio.h>
void main()
{
int a=15,b=20,sum;
message();
}
message(int c,int b)
{
c=b;
printf("%d",c);
}


the o/p of this code was the value of a i.e 15. but i wanted 2 display the value of b i.e. 20.
pls tell me how and wats happening here

#include<stdio.h>
#include<conio.h>
void main()
{
int a=15,b=20,sum;
message(a,b);
}
message(int c,int b)
{
printf("%d",b);
}

You should at least got some errorcodes when compiling this a C code.
The function 'message' must always be calles with parameters, as B-Con suggested: message(a, b); This way the values of a and b are passed into the function.
Also a function has to be defined with a return type:
void message(int a, int b)

So what environment are you using?

Also the output of the program would be 0 or an uninitialized value. Variables a and b are local values within the fuction main. Therefore the value of a (15) can never be shown by the printf in the function message.


Basically I would suggest:

#include<stdio.h>
#include<conio.h>
void main()
{
int b=20;
message(b);
}

void message(int b_copy)
{
int c = b_copy;
printf("%d",c);
}