C Programming - Functions - Discussion

@ Khushboo
Your are right, in C RETURN TYPE IS NOT NEEDED when we write FUNCTION DEFINITION, it is needed only at the FUNCTION DECLARATION.
So for this program Re-Declaration of variable 'a' is the only problem.

For example refer the below program which doesn't have return type at definition.

#include<stdio.h>
int add(int,int);
int main()
{
int a,b,c;
printf("Enter two numbers :");
scanf("%d" "%d",&a,&b);
c = add(a,b);
printf("Addition Value = %d",c);

return 0;
}
add(int x, int y)
{
int z;
z = x + y;
return z;
}

@ Khushboo and @ Hakkim when I am running program without mentioning the return type of main () and I didn't return anything then it is giving an warning that "function should return a value. " so default return type of main () should be int. Please give your responce.

At many places we see void as default return type of function for example in declaration of main we only write main ()
{} and do not return any value so anyone please explain this confusion. ?

The default return type of any function is "int", so it is useless to write
"int f(int a, int b)".

Even if we use return in the program, instead of using getch() ; the program doesn't run. Can anyone clear my doubt ?

int a; //declaration part
a=20; //defination part
so why its give error?
please explian...

@Ashish:

f(int a,int b)// a is declared as int.
{
int a; // error: Redeclaration.
...
}

@Ganesh yeah!

True. The default return type may be void.

We can't re-declare any variable in the same block.

Even return type is also missing rite?