111-D Statement is unreachable on Return 0

Question

int main(void) {

    TIM4_Init();
    setSysTick();

    while (1) {
        TIM4->CCR1 = 600;       // 600 == 0.6 ms  -> 0'
        Delay(700);

        TIM4->CCR1 = 1500;      // 1500 == 1.5 ms -> 90'
        Delay(700);

        TIM4->CCR1 = 2100;      // 2100 == 2.1 ms -> 150'
        Delay(700);
    }

    return 0; 
}

Above is part of the code I'm currently working on. I'm getting a warning saying that 'Statement is unreachable' at the Return 0, and I couldn't figure out why.

Because the `return` is not reachable. The `while` loop never terminates. Really, not that difficult. — Eugene Sh., Apr 27 '17 at 20:17
You should be grateful that you get a compiler error message that is actually meaningful and correct. — ThingyWotsit, Apr 27 '17 at 20:38

score 4 · Answer 1 · answered Apr 27 '17 at 20:19

4

The while (1) loops forever, so without a way to get out if the loop, you won't get to the return.

To get rid of the warning, you can change main() to return void

void main (void) { }

answered Apr 27 '17 at 20:19

Justin J.

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`void main` is a non-standard C. It might be available as an extension though. – Eugene Sh. Apr 27 '17 at 20:20
void main(void) is allowed since C99, and required for some microcontrollers. However, may be compiler specific. [See discussion about int main() vs void main()](http://stackoverflow.com/a/9356660/7928083) – Justin J. Apr 27 '17 at 23:38
Wrong!! The return value is needed in some toolchains (actually in the exit code) to determine how to end the program. main is not a part of compiler - it is just called by the startup code. C99 standard advices int return value - but it can be implementation defined as well. – 0___________ Apr 29 '17 at 13:53

score 1 · Accepted Answer · answered Apr 27 '17 at 23:41

1

Delete return 0; :) The compiler will notice that there is no way to reach end of main(), and it will not generate warning for reaching the end of int function without the return

answered Apr 27 '17 at 23:41

0___________

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111-D Statement is unreachable on Return 0

2 Answers2