在下面的程序中，我期望无限循环作为输出。 但是输出是0，请帮我解释一下它背后的概念

Question

void main()
{   
     int i;
     int s=0;
     while(i<30)
     s+=i;
     i++;
     printf("Sum is %d",s);
}

/ output is 0,how? I was expecting infinite loop. /

Answer 1

i is uninitialized. It can have any value. If it has a value greater/equal than 30, the loop will not execute and s remains 0.

Answer 2

void main()
{   
     int i;
     int s=0;
     while(i<30)
     s+=i;
     i++;
     printf("Sum is %d",s);
}

i is not being initialized properly, leading to undefined behaviour. Change it to:

int main(void)
{   
     int i = 0;
     int s=0;
     while(i<30)  // Infinite loop per OP's expectation
       s+=i;
     i++;
     printf("Sum is %d",s);
return 0;
}

Note (Thanks @MikeCAT): To avoid implementation based messing, replace void main() with int main(void) .