Answer:
Explanation:
A null pointer is pointing to nothing, if we can detect if a pointer is null, we can use an "IF" because a null pointer always going to be false, a null pointer even can block an application, because is a result of undefined behavior, it can even cause problems because the compiler can’t tell whether we mean a null pointer or the integer 0, there is a confusion in this kind of pointers.
 
        
             
        
        
        
Answer:
len()function:
Explanation:
that's for python btw
i also know java if you want a java version
 
        
             
        
        
        
The for cheaters? Like what kind of Cheaters?
Explanation:
 
        
             
        
        
        
This website has an article about the on-board diagnostics system (OBD system) which turns on the Check Engine light in a motorized vehicle: https://motorist.org/articles/check-engine-light
Hope it helps you!
        
             
        
        
        
Answer:
Healthy plant growth follows from sufficient water.
Contrapositive: If water is insufficient, then there isn't healthy plant growth
Increased availability of information is a necessary condition for further technological advances
Contrapositive: Absence of further technological advances implies decreased availability of information.
 Errors were introduced only if there was a modification of the program.
Contrapositive: If there wasn't any modification of the program then error was not introduced into the program
 Fuel savings implies good insulation or storm windows throughout.
Contrapositive: The absence of good insulation or storm windows throughout implies that there is no fuel savings.
Explanation:
A contrapositive statement is formed from a conditional statement as we can see from the answers above.
In a contrapositive statement, we just interchange the hypothesis and the conclusion of the inverse statement. 
This implies that, when the converse of the statement is true, then the inverse of the statement is also logically true.