CODEWITHSUNDEEP
objective-cxcodecompiler-warnings
Abdelrahman Eid
Abdelrahman Eid

Reputation: 901

"Variable may be uninitialized when used here" Xcode compiler warning

So I wrote this little program that gives this warning despite the fact that I have the variable initialized, not a duplicate question.

int main(int argc, const char * argv[]) {
    @autoreleasepool {

        int num1, num2, product, largestProduct = 0;

        while (num2 < 1000) {

            while (num1 < 1000) {

                product = num1 * num2;

                if (isPalindrome(product)) {

                    largestProduct = product>largestProduct?product:largestProduct;
                }

                num1++;
            }

            num1 = 0; //If I delete that line the warning disappears.
            num2++;
        }

       NSLog(@"%i", largestProduct);

    }
    return 0;
}

The weird thing is if I delete that commented line the warning disappears, and if I initialize num1 individually it also disappears. Am I doing something wrong or is that a bug in Xcode?

Upvotes: 0

Views: 23167

Answers (2)

Ayush Goel
Ayush Goel

Reputation: 3144

In addition to @rmaddy's answer, you could also move the line num1 = 0 above the second while loop. That way, when you actually use the variable num, it would have an explicit initialisation value.

int main(int argc, const char * argv[]) {
    @autoreleasepool {

        int num1, num2, product, largestProduct = 0;

        while (num2 < 1000) {

            num1 = 0; //Value initialised here.

            while (num1 < 1000) {

                product = num1 * num2;

                if (isPalindrome(product)) {

                    largestProduct = product>largestProduct?product:largestProduct;
                }

                num1++;
            }

            num2++;
        }

       NSLog(@"%i", largestProduct);

    }
    return 0;
}

Upvotes: 0

rmaddy
rmaddy

Reputation: 318774

The line

int num1, num2, product, largestProduct = 0;

only initializes largestProduct to 0. None of the other variables on that line are explicitly initialized.

It's arguably poor practice to declare multiple variables on one line.

I would suggest:

int num1 = 0;
int num2 = 0;
int product = 0;
int largestProduct = 0;

This is easier to read and debug.

But if you really want one line, do:

int num1 = 0, num2 = 0, product = 0, largestProduct = 0;

Upvotes: 2

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