calculator program in c language

The main thing in the source
code below in the scanf which
scans the input as number
symbol number just as in case
of normal calculator.
Code: C
#include
float add(float,float);
float sub(float,float);
float product(float,float);
float divide(float,float);
void main()
{
float n1,n2;
char sym,choice;
printf("This Program is a
program for calculator\n\n");
scanf("%f%c%
f",&n1,&sym,&n2);
if(sym=='+')
printf("\n%f",add(n1,n2))
;
if(sym=='-')
printf("\n%f",sub(n1,n2));
if(sym=='*')
printf("\n%f",product
(n1,n2));
if(sym=='/')
printf("%f",divide(n1,n2))
;
printf("\nDo you wish to
continue[y/n]");
scanf("%s",&choice);
if(choice=='y'||
choice=='Y')
main();
}
float add(float m1,float m2)
{
return(m1+m2);
}
float sub(float m1,float m2)
{
return(m1-m2);
}
float product(float m1,float
m2)
{
return(m1*m2);
}
float divide(float m1,float m2)
{
return(m1/m2);
}