Consider the following if statement:

if(dragOperation != NSDragOperationCopy && NSPointInRect(currentMouseLocation, self.bounds)){
    //do something
}

Even though you may have worked out what the condition represents, it probably took you a little longer than it should. It’s complicated, making it time consuming to read, and prone to bugs upon modification. Thankfully, there is an easy remedy:
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The ternary conditional operator (?:) can be used as a short-hand version of an if statement. It is a feature of many languages.

For example, this code:

int height;
if(isTall)
    height = 50;
else
    height = 10;

can be better written as:

int height = isTall ? 50 : 10;

The ?: operator is good for replacing very simple if statements, but is bad for complicated if statements as it can harm readability.

Can you tell what is wrong with the abstraction in this class interface?

@interface EmployeeList
-(void) addObject:(Employee*)anEmployee;
-(void) removeObject:(Employee*)anEmployee;
-(NSUInteger) numberOfEmployees;
@end

Here is the answer:
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Having one exit point (return) from a function is a good thing. Here is an example of a single exit point:

int MyArray::indexOfElement(int elementToFind){
	int foundIndex = ELEMENT_NOT_FOUND;
 
	for(int i = 0; i < m_numberOfElements; ++i){
		if(this->elementAtIndex(i) == elementToFind){
			foundIndex = i;
			break;
		}
	}
 
	return foundIndex;
}

Having multiple exit points can be bad. Here is an example of multiple exit points:

int MyArray::indexOfElement(int elementToFind){
	for(int i = 0; i < m_numberOfElements; ++i){
		if(this->elementAtIndex(i) == elementToFind){
			return i;
		}
	}
 
	return ELEMENT_NOT_FOUND;
}

Why are multiple exit points bad? Because I say so. They are also bad for these two reasons:

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