left-hand operand of comma has no effect?

Question

I\'m having some trouble with this warning message, it is implemented within a template container class

int k = 0, l = 0;
    for ( k =(index+1), l=0; k <         


        

Answer 1

The expression k < sizeC, l < (sizeC-index) only returns the result of the right-hand test. Use && to combine tests:

k < sizeC && l < (sizeC-index)

Answer 2

Change to:

for ( k =(index+1), l=0; k < sizeC && l < (sizeC-index); k++,l++){

When you have a comma expression is evaluated the rightmost argument is returned so your:

 k < sizeC, l < (sizeC-index)

expression evaluates to:

 l < (sizeC-index)

and thus misses

 k < sizeC

use the && to combine the conditions instead.

Answer 3

The comma expression a,b,c,d,e is similar to

{
  a;
  b;
  c;
  d;
  return e;
}

therefore, k<sizeC, l<(sizeC - index) will only return l < (sizeC - index).

To combine conditionals, use && or ||.

k < sizeC && l < (sizeC-index)  // both must satisfy
k < sizeC || l < (sizeC-index)  // either one is fine.