CODEWITHSUNDEEP
cfor-loopoutput
Âftãb Bãlôçh
Âftãb Bãlôçh

Reputation: 53

Confusing Output of C Program

Why compiler shows the value of x as 0 if I define int x; inside of for loop. But when removing int x from for loop gives the value of x as 10.

#include<stdio.h>
int main() {
    int x = 0, i;
    for(i = 1; i <= 10; i++) {
        int x;
        x = 10;
    }
    printf("%d", x);
}

Upvotes: 1

Views: 98

Answers (3)

Ameer Shalabi
Ameer Shalabi

Reputation: 73

As explained before, if you define a variable inside the for loop int x; x = 10; it will create a new variable that is only accessed inside the for loop.

So when you create variable x in main then create variable x in the for loop, you are currently referring the print printf("%d", x); to the first x declared in main and that is why it is printing 0. This is because you initiated it to 0 in the line int x = 0, i; and it never changed. You never actually printed the x you initiated in the for loop.

But when you remove the int x; form the for loop, there is only one x initiated and you changed the value of x to 10 inside the loop. When you print x it gives you 10 which is the value that was assigned to it inside the for loop.

Hope this is not confusing.

Upvotes: 1

Aditya Satpute
Aditya Satpute

Reputation: 151

Because the scope of int x inside the for loop is limited to that for loop only.

for(i=1;i<=10;i++) { int x; x=10; /limited to this loop only, can't use outside of for loop/ }

And int x outside of for loop but inside main() function would be available to all function inside main()

If you want to get value of i you may try this:

x=i;

instead of

int x; x=10;

Upvotes: 2

Atle
Atle

Reputation: 1877

If you have int x inside your for-loop, you create a new x variable. That means that you effectively have two x variables in your program, one which can be accessed from your main()-function and one which only can be accessed inside the for-loop. If you access x from within the for-loop, the compiler will choose the closest one.

If you were not to have int x inside your for-loop, there would only be one x and your program would output 10.

Upvotes: 2

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