sharadpro

Quoting the book Thinking in C++,
while((char c = cin.get()) != 'q')
The addition of the extra parentheses would seem like an innocent
and useful thing to do, and because you cannot use them, the
results are not what you might like. The problem occurs because
‘!=’ has a higher precedence than ‘=’, so the char c ends up
containing a bool converted to char. When that’s printed, on many
terminals you’ll see a smiley-face character.

The author uses while( char c = cin.get() != 'q') to check if the character being input is q and says that extra () can't be used as stated above.

Is it ok? AFAIK , if the () are not used , then it is a problem and not otherwise.If not used , cin.get() != 'q' would be evaluated first and the bool value assigned to char

Arevos

I suspect what the author means is:
Though the whole paragraph is worded rather confusingly.

Suffice to say, boolean operators have a higher precedence than the assignment operator, thus:
Is equivalent to:
In other words, x is assigned a boolean value. This is why you have to explicitly bracket the "x = y", when dealing with while loops of this type.
Precedence is all about what operators are evaluated first. You may remember from basic math that the multiplication operator has a higher precedence than the addition operator. So this:
Is the same as:
Lower precedence operators are evaluated after ones with higher precedence, so multiplication takes place before division. The assignment operator has one of the lowest precedences of all the operators, and thus is evaluated last in the majority of circumstances.