Doubt in For loop

[Seema Sharma]

Hi,
Please help me to understand the output for the following question.

class JMM125 {
static int i;
public static void main(String args[]) {
for (i=1; i<3; i++) {System.out.print(i);} // 1
for (int i=1; i<3; i++) {System.out.print(i);} // 2
int i; // 3
for (i=0; i<2; i++) {System.out.print(i);} // 4
System.out.print(JMM125.i);
}}

What is the result of attempting to compile and run the program?

a. Prints: 1212010
b. Prints: 1212013
c. Compile-time error at line 1
d. Compile-time error at line 2
e. Compile-time error at line 4
f. Run-time error
g. None of the above

what i understand from the above question is that "int i" is different each time. It is declared each time in the FOR LOOP. So the answer should be NONE OF THE ABOVE.

But the correct answer is 1212013 (option b).

[Paul Napauleon]

the static int i is used in the first for loop. there is no new variable declared in the loop.

[Murali Kakarla]

Hi Seema

class JMM125 {
static int i;
public static void main(String args[]) {
for (i=1; i<3; i++) {System.out.print(i);} // 1
for (int i=1; i<3; i++) {System.out.print(i);} // 2
int i; // 3
for (i=0; i<2; i++) {System.out.print(i);} // 4
System.out.print(JMM125.i); //5
}}

At Line 1 -> i is static variable of JMM125. Hence prints 12 and JMM125.i=3
At Line 2 -> i is local variable of for loop at line 2. Hence prints 12
At Line 4 -> i is local variable of main method at line 3. Hence prints 01
At Line 5 -> Prints JMM125.i=3

Murali...

[mo shaik]

   
 
hello seema,
i your code what u r doing is 
1)  i =0 initially u assigned to 1 in for loop which prints 12 to the condition then it exists now  the static var i=3
 
2)  now i =0 this is not global var i is local to the for loop
 then again it prints to the condit
 
3)now again i=0 this is also local which prints the condition.
 
 
4)u r asking to print the value of class global var which i=3.
 
i think this is clear 
thank u
 

 

 

[Priyam Srivastava]

just to add to Murali's explanantion, when you have a local variable with same name as that of static or instance variable, then if you are not using the class name to call the static variable or 'this' reference for instance variable, compiler always gives preference to local variable of the same name...

class A {
int a;
A(int a) {
a=a;
}
}

here both a refers to local variable of the constructor.
[ July 24, 2007: Message edited by: Priyam Srivastava ]

[Prasad Tamirisa]

     System.out.print([B]JMM125.i[/B]);

If you observe the above code. I has been accessed using the name of the class but not with its instance. So, in the first loop the variable i has been reached its value 3.

[Seema Sharma]

Thanks all for explaining.. i got it now.