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ccomparison-operators

Why is while (1 < a < 5) an infinite loop?

int a = 2;   
while (1 < a < 5)  {
      printf("%d\n", a);
      a = a + 1;
}

In a C program, I have used the above code, but it is always counting infinitely. That means the test condition of the while loop is always true. But I could not understand why this is happening.

Solution

  • 1 < a < 5 is grouped as (1 < a) < 5.

    For your value of a, 1 < a returns 1 (true), so now your expression becomes 1 < 5, which always evaluates to 1, that's why you end up with an infinite loop.

    The behavior you want can be obtained by writing while((1 < a) && (a < 5)) instead.