conditional-operator

From what I have read, I found that a built-in ternary operator does not exist (I will be happy to know more about it.). I found the following code as a substitute: def val(): var = float(raw_input("Age:")) status = ("Working","Retired")[var>65] print "You should be:",status I couldn't understand how this code works; can anyone explain me how actually the code is working? I am also interested to know why the ternary operator doesn't exist; any references or links about this will be ore useful. I'm running Python 2.6.4 on Windows Vista. Python has a construct that is sort of like the ternary

I have this extract of C# 2.0 source code: object valueFromDatabase; decimal result; valueFromDatabase = DBNull.Value; result = (decimal)(valueFromDatabase != DBNull.Value ? valueFromDatabase : 0); result = (valueFromDatabase != DBNull.Value ? (decimal)valueFromDatabase : (decimal)0); The first result evaluation throws an InvalidCastException whereas the second one does not. What is the difference between these two? Eric Lippert UPDATE: This question was the subject of my blog on May 27th 2010 . Thanks for the great question! There are a great many very confusing answers here. Let me try to

Possible Duplicates: Nullable types and the ternary operator. Why won’t this work? Conditional operator assignment with nullable<value> types? This will not compile, stating "Type of conditional expression cannot be determined because there is no implicit conversion between 'System.DateTime' and ''" task.ActualEndDate = TextBoxActualEndDate.Text != "" ? DateTime.Parse(TextBoxActualEndDate.Text) : null; This works just fine if (TextBoxActualEndDate.Text != "") task.ActualEndDate = DateTime.Parse(TextBoxActualEndDate.Text); else task.ActualEndDate = null; This doesn't work because the compiler

I'm trying to use return in a ternary operator, but receive an error: Parse error: syntax error, unexpected T_RETURN Here's the code: $e = $this->return_errors(); (!$e) ? '' : return array('false', $e); Is this possible? Thanks! This is the correct syntax: return !$e ? '' : array('false', $e); Sysyphus Close. You'd want return condition?a:b It doesn't work in most languages because return is a statement (like if , while , etc.), rather than an operator that can be nested in an expression. Following the same logic you wouldn't try to nest an if statement within an expression: // invalid because

In the Android open-source qemu code I ran across this line of code: machine->max_cpus = machine->max_cpus ?: 1; /* Default to UP */ Is this just a confusing way of saying: if (machine->max_cpus) { ; //do nothing } else { machine->max_cpus = 1; } If so, wouldn't it be clearer as: if (machine->max_cpus == 0) machine->max_cpus = 1; Interestingly, this compiles and works fine with gcc, but doesn't compile on http://www.comeaucomputing.com/tryitout/ . This is permitted in GNU as an obscure extension to C 5.7 Conditionals with Omitted Operands The middle operand in a conditional expression may be

The following tag of JSTL can be used to set a value to a variable in a request scope. <c:set var="value" scope="request" value="someValue"/> I want to check conditionally, if the variable value being set is empty or not and display the result accordingly something like the following, using <c:when>...</c:when> . <c:choose> <c:when test="${not empty value}"> <c:out default="None" value="${value}"/> </c:when> <c:otherwise> <c:out default="None" value="None"/> </c:otherwise> </c:choose> I want to reduce the line of code using a ternary expression like, <c:out default="None" value="${not empty