What does this warning mean (i and j are not constants):
I have been trying to Google this but it does not give me any results.
warning: comparison of constant 10 with boolean expression is always true [-Wtautological-constant-out-of-range-compare]
if ((0<=i<=10)&&(0<=j<=10)){
In my program, i and j are not constant values and they do change.
In C, chaining of relational operators like this are not valid design. Thus,
(0<=i<=10)
is not doing what you think it should be doing. it is getting evaluated as
((0<=i) <= 10 )
which is basically either
0 < = 10, producing 1 (considered TRUE value)1 < = 10, also producing 1 (considered TRUE value)sadly, both of which are way out than the expected path.
Solution: you need to break down your condtion check like
(0 <= i) && ( i<=10)
I believe you need to understand what's going on in your statement at a deeper level.
0<=i is a boolean expression, it will become true or false.
The result of that expression is then compared with 10.
So you end up with true <= 10 or false <= 10.
I think you meant to write
if ( ( 0 <= i ) && ( i <= 10 ) )
You cannot connect clauses together the way you did.
The other answers have already explained the core problem. You can use:
if ( ( ( 0 <= i) && (i <= 10)) && ( ( 0 <= i) && (i <= 10)) )
to resolve your problem.
My recommendation will be to wrap that logic in a function.
int isInRange(int x, int lower, int upper)
{
return (lower <= x && x <= upper);
}
and use
if ( isInRange(i, 0, 10) && isInRange(j, 0, 10) )