Can you use a variable before it has been initialized?

Notice that a variable that is not initialized does not have a defined value, hence it cannot be used until it is assigned such a value. …

Should you always initialize variables C++?

Initializing variables (implicitly or explicitly) is crucial. Not initializing a variable is always an error (they might be initialized implicitly, however. See below). Modern compliers like the C# compiler (as an example) treat this as an error and won’t let you execute the code.

What happens if you don’t initialize a variable before use?

When you declare but do not initialize a variable, it is in an indeterminate state. If you always assign some useful value to that variable before you use it, then the code remains happy and well defined. If you use the variable while it is in that indeterminate state, Undefined Behavior results.

Should you initialize variables in C?

In general, there’s no need to initialize a variable, with 2 notable exceptions: You’re declaring a pointer (and not assigning it immediately) – you should always set these to NULL as good style and defensive programming. If, when you declare the variable, you already know what value is going to be assigned to it.

Is it necessary to declare a variable before using it if so then explain?

It’s best to declare variables when you first use them to ensure that they are always initialized to some valid value and that their intended use is always apparent. More importantly, though, by declaring the variable when it is first used, you give it context.

Why should you initialize a variable when you first declare it?

Rationale: It’s best to declare variables when you first use them to ensure that they are always initialized to some valid value and that their intended use is always apparent. You give it a reason to exist, which goes a long way towards understanding what the variable is for. …

Should I initialize variables?

Because, unless the variable has static storage space, it’s initial value is indeterminate. You cannot rely on it being anything as the standard does not define it. Even statically allocated variables should be initialized though. Just initialize your variables and avoid a potential headache in the future.

When should you initialize variables?

When you declare a variable, you should also initialize it. Two types of variable initialization exist: explicit and implicit. Variables are explicitly initialized if they are assigned a value in the declaration statement. Implicit initialization occurs when variables are assigned a value during processing.

Why do we need to declare a variable?

Declaring Variables Before they are used, all variables have to be declared. Declaring a variable means defining its type, and optionally, setting an initial value (initializing the variable). Variables will roll over when the value stored exceeds the space assigned to store it.

How to declare and initialize a variable in C?

Declaring & initializing C Variable 1 First, you need to declare a variable in the C program before to use it. 2 Memory space is not created for a variable during a declaration. It happens only on the variable definitions. 3 Variable initialization assigs a value to the variable.

Is it better to declare a variable close to its use?

The few extra characters (like ” = 0 “) typed during development may save hours of debugging time later, particularly when it is forgotten that some variables remained uninitialized. In passing, I feel it is good to declare a variable close to its use.

Why should variables not be initialised before using?

There is absolutely no reason why variables shouldn’t be initialised, the compiler is clever enough to ignore the first assignment if a variable is being assigned twice. It is easy for code to grow in size where things you took for granted (such as assigning a variable before being used) are no longer true. Consider:

When is it harmful to initialize a variable with a dummy?

When a meaningful value for the variable can’t be determined until subsequent code has completed execution. In this case, it’s actively harmful to initialize the variable with a dummy value such as zero/NULL, as this prevents the compiler from warning you if you have some code paths where a meaningful value is never assigned.