wrong expression result linq

Question

I want to get records with parentIds. But this Linq expression gave me elements with 0 parentId value.

var orders =
 OrderEquityTransactions.AsParallel().Where(
 o => o.FinancialInstrumentId == financialInstrumentPrice.FinancialInstrumentId &&
 o.ParentId != 0 &&
 o.DebitCredit == "A" ? o.Price >= financialInstrumentPrice.Price : o.Price <= financialInstrumentPrice.Price).ToList();

After some digging I rewrote expression with additional two brackets and problem solved.

var orders =
 OrderEquityTransactions.AsParallel().Where(
 o => o.FinancialInstrumentId == financialInstrumentPrice.FinancialInstrumentId &&
 o.ParentId != 0 &&
 (o.DebitCredit == "A" ? o.Price >= financialInstrumentPrice.Price : o.Price <= financialInstrumentPrice.Price)).ToList();

What is the reason of this behavior?

• Frédéric Hamidi: Operator precedence?

Answer 1

Because in the first case it was interpreted as:

o => (o.FinancialInstrumentId == financialInstrumentPrice.FinancialInstrumentId 
 && o.ParentId != 0 && o.DebitCredit == "A") 
 ? o.Price >= financialInstrumentPrice.Price 
 : o.Price <= financialInstrumentPrice.Price

which is absolutely another.

Please, read this article on operator precedence.
Ternary conditional operator has the lower priority than conditional AND.

Answer 2

As per Operator precedence and associativity, conditional ANDs have a higher precedence than the conditional operator. So C# evaluates your expresion like this:

(o.FinancialInstrumentId == financialInstrumentPrice.FinancialInstrumentId 
 && o.ParentId != 0 && o.DebitCredit == "A")
 ? o.Price >= financialInstrumentPrice.Price
 : o.Price <= financialInstrumentPrice.Price