Ace Test series

Question

What will be the output?

Comments

static 'a' of f() is updated not static 'a' of main.

---

Suppose I call another function g() after f() that prints the value of 'a'. Will it print a of main or a of f()?

void g()

{

printf("%d", a)

}

---

What i understood from your comment is that the main function will look like this -->

int main()

{

static int a=1;

f();

a*=2;

f();

printf("%d",a);

g();

}

Since your g() does not have any 'a' defined in it so it will look for 'a' in it's next outer block i.e. the global scope. If it finds a variable named 'a' in global scope then it will print it's value [ this is due to the reason that C follows static scoping]. Here in this case there is a global 'a'. As no value has been assigned to it, it will print "0" [ by default global variables have value=0].

The static 'a' of main would have been printed by C had followed dynamic scoping rules. In dynamic scoping the called function after failing to find a's definition inside it's body, searches in the function that has called it i.e. the main function. If main does not have any 'a' then it searches in the global scope. If that also fails then there is an error.

Answer 1

1) int a,b; ---- a,b are global variables ===> initialized by their default values ==> a=0, b=0. but note that main have variable a, therefore it can't access global a but it can access global b, coming to function f() it have variable a and variable b in it's function as local variables, therefore it can not access either global a or global b

2) void f(); ---- declaring f is a function which accepts no parameters(not compulsory) and no return type

3) int main()

4) {

5)          static int a=1; ----> static variable, for avoiding confusion, name it as main.a=1

6)         f(); ------------> Calling function f()

goto 11th line, creating and initializing f.a=2, f.b=2, f.a value updated as 4 in 15th line, after execution of 15th line f.b updated as 3

by 16th line printing 4,3

by 17th line, f.b is removed but f.a is still in static memory with the value 4

7)         a*=2; ===> a=a*(2) -----> main.a = main.a*(2) ===> main.a updated to 2

8)         f();  ------------> Calling function f()

goto 11th line, creating f.b=2 only, already f.a created and  f.a value is 4. f.a value updated as 8 in 15th line, after execution of 15th line f.b updated as 3

by 16th line printing 8,3

by 17th line, f.b is removed but f.a is still in static memory with the value 8

9)         printf("%d..%d",a,b); ----> accessing main.a, global.b ===> print 2,0

10) }

11) void f()

12) {

13)         static int a=2;

14)         int b=2;

15)          a*=b++; ====> a=a*(b++);

16)         printf("%d..%d",a,b);

17)  }

Comments

 main()
{
    static int i=5;
    if(--i){
        main()
         {
          static int i=5;
          if(--i){
           main()
           ...............................//going infinite times

        printf("%d ",i);
    }
    printf("%d ",i);

    }

}

In this Code you are again defining the static variable ===> go to infinite loop

 

 

#include <stdio.h>

int main()

{

    static int i=5;

    if(--i){

        main();

        printf("%d ",i);

    }

}

but in this code, you are calling the function ===> does not go to infinite loop

---

I havenot got .

which function??

main() function is called only and that should go to infinite loop. Is not it?

just dryrun code

I havenot got where is fault in my logic

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mam, function calling is different and function definition is different...

if you are calling that function, no new static variables created if already those are created.

But by definition of a function, you are always creating a new static variable.

 

1) #include <stdio.h>

2) int main()

3) {

4)    static int i=5;

5)    if(--i){

6)        main();

7)        printf("%d ",i);

8)    }

9) }

 

while you encounter at 4 ( at first time ), static variable i is created and initialize to 5, but at line 6, you are calling main function again, then again you encounter line 4, but this time you are not creating a new static variable i , it's just read the value.