C static variable in function

Static elements are allocated storage only once in a program lifetime in static storage area. And they have a scope till the program lifetime. Static Keyword can be used with following. Static variables when used inside function are initialized only once, and then they hold there value even through function calls.

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If we do not use static keyword, the variable count, is reinitialized everytime when counter function is called, and gets destroyed each time when counter functions ends. But, if we make it static, once initialized count will have a scope till the end of main function and it will carry its value through function calls too.

Static keyword works in the same way for class objects too. Objects declared static are allocated storage in static storage area, and have scope till the end of program. Static objects are also initialized using constructors like other normal objects. Assignment to zero, on using static keyword is only for primitive datatypes, not for user defined datatypes. You must be thinking, why was the destructor not called upon the end of the scope of if condition, where the reference of object obj should get destroyed.

This is because object was staticwhich has scope till the program's lifetime, hence destructor for this object was called when main function exits. Static data members of class are those members which are shared by all the objects. Static data member has a single piece of storage, and is not available as separate copy with each object, like other non-static data members. Static member variables data members are not initialied using constructor, because these are not dependent on object initialization.

Also, it must be initialized explicitly, always outside the class. If not initialized, Linker will give error. Once the definition for static data member is made, user cannot redefine it. Though, arithmetic operations can be performed on it.

It can be called using an object and the direct member access. But, its more typical to call a static member function by itself, using class name and scope resolution :: operator. These functions cannot access ordinary data members and member functions, but only static data members and static member functions. It doesn't have any "this" keyword which is the reason it cannot access ordinary members. We will study about "this" keyword later. Made with by Abhishek Ahlawat.

Ruby Servlet JSP. Operating System. Computer Architecture. Jenkins Maven. Apache Cordova Drools.The following are four types of storage class available in C language. Before moving ahead, lets quickly understand the difference between life time and scope of a variable. A region in code where a variable can be accessed is known as its scope and the duration during which a variable remains active is known as its life time. Any local or global variable can be made static depending upon what the logic expects out of that variable.

Lets consider the following example :. Lets look at the output :. The output above is as expected. So, is everything fine here?

Well, there is a hidden problem in the code. The logical problem remains the same here too. Each of these function returns the address of its local variable. The output above is not as per expectations. Its just the correct scenario that exposed the loophole in the code. Lets go a bit more deep to see what happened after address of local variable was returned.

See the code below :. The code is above is modified to print the address of the functions and the address of their respective local pointer variables.

c static variable in function

Here is the output :. So, now we see what that the root of the problem is the life time of the pointer variables.

As already discussed the static storage class makes the lifetime of a variable equal to that of the program. So, lets make the local pointer variables as static and then see the output :.

So we see that after making the variables as static, the lifetime of the variables becomes equal to that of the program. In case where code is spread over multiple files, the static storage type can be used to limit the scope of a variable to a particular file.In this article, I emphasize the static keyword's various purposes in Java.

There are 57 keywords in Java, but this static keyword is a special one that can be used in four different applications. In this article, I will give a brief tutorial on the static keyword. A static keyword can be used with blocks, variables, methods, and classes. As we know, in object-oriented programming everything is based upon objects.

c static variable in function

If you want to access the variable or method, you need to create an object. However, if we declare a static member, it provides a feature so we can access these without creating the object or object reference. It's executed only once and is usually used to initialize the variables.

In Java, if we want to print even a hello world, we have to write the code within the static main function or you can access the method through an object. If we want to do something without disturbing objects, then we can do that process with the help of a static block. The main purpose of a static block is to initialize the static variable, as we have shown in the example.

On the other hand, constructors are used to initialize local variables. Note: we cannot initialize a non-static instance variable inside the static block. That variable value will be shared among all the objects.

We access the local variable via the help of objects, but in the case of static variables, we can call them through the class name, since it's common to all the objects. The object will create a memory in heap, but the static variable will not be in the heap. Instead, it will be in the class loader memory.

If we use static variable it calls once irrespective of the number of objects. In the case of constructors, the number of times execution of the constructors will be based on the number of objects. So this is why we call the static variable, it is better for our project with respect to memory management.

Static Keyword in Java

Here's a demo to explain the static variable with Java code. Consider we are creating a project with employee details and the fields are as follows, employee ID, salary, and CEO of the company.

Here, the first two fields are a variable, whereas the CEO of the company will be the same for all the employees. In Java, we have the main function that is always declared as static. Because that is the first function, it has to be executed, even before creating an object.

In a static function, we cannot access nonstatic variables. In the same way, they can call other static functions only directly. But only the inner class can be created using a static keyword.

A static class cannot access the non-static methods and variables of the outer class. I hope this article helped give some clarity to the static keyword.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Having a header that defines some static inline function that contains static variables in it, how to achieve merging of identical static local variables across all TUs that comprise final loadable module?.

In a less abstract way:. It is quite expected that both TUs receive own copies of getPtr. Though inside each TU getPtr. This can be confirmed by inspecting final loadable binary:. At the same time I'm looking for a way of how to share getPtr. Is there any attribute or other source-level not a compiler option way to achieve merging such objects? If I understand correctly what you want, you can get this effect by simply declaring a global variable.

It will be initialized to NULLwhich is just what you want. So nothing besides inc. This is actually an extension to standard C mentioned in Annex J. It's documented under the -fcommon compiler option which is enabled by default. It's typically implemented by putting the variable in a common section, and the linker then merges all instances together, just as you suggest.

But the code above shows how to access the feature without needing to use attributes or other obscure incantations. Of course, that may cause trouble if -fno-common was being used for a reason Learn more. How to merge statics for all instances of header-defined inline function?

C Part 13 Local Static and Global Variables

Ask Question. Asked 4 days ago.

c static variable in function

Active 4 days ago.Prerequisite : Static variables in C. Static keyword has different meanings when used with different types. We can use static keyword with:.

c static variable in function

You can see in the above program that the variable count is declared as static. So, its value is carried through the function calls. The variable count is not getting initialized for every time the function is called. Static variables in a class : As the variables declared as static are initialized only once as they are allocated space in separate static storage so, the static variables in a class are shared by the objects.

There can not be multiple copies of same static variables for different objects. Also because of this reason static variables can not be initialized using constructors. You can see in the above program that we have tried to create multiple copies of the static variable i for multiple objects. So, a static variable inside a class should be initialized explicitly by the user using the class name and scope resolution operator outside the class as shown below:.

In the above program the object is declared inside the if block as non-static. So, the scope of variable is inside the if block only. So when the object is created the constructor is invoked and soon as the control of if block gets over the destructor is invoked as the scope of object is inside the if block only where it is declared.

Let us now see the change in output if we declare the object as static. You can clearly see the change in output. Now the destructor is invoked after the end of main. This happened because the scope of static object is through out the life time of program. Static functions in a class : Just like the static data members or static variables inside the class, static member functions also does not depend on object of class.

Static member functions are allowed to access only the static data members or other static member functionsthey can not access the non-static data members or member functions of the class.

This article is contributed by Harsh Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute. See your article appearing on the GeeksforGeeks main page and help other Geeks. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. Writing code in comment? Please use ide. Prerequisite : Static variables in C Static keyword has different meanings when used with different types.

GfG obj1. GfG obj2. GfG obj. GfG::printMsg.

C Static Variables and Static Functions Explained with Examples

Load Comments.Static variables have a property of preserving their value even after they are out of their scope! Hence, static variables preserve their previous value in their previous scope and are not initialized again in the new scope. A normal or auto variable is destroyed when a function call where the variable was declared is over. See memory layout of C programs for details.

For example in the below program, value of x is printed as 0, while value of y is something garbage. See this for more details. For example, following program fails in compilation. The purpose of these is to limit scope of a variable or function to a file. Please refer Static functions in C for more details. The reason is C compiler requires the entire structure elements to be placed together i.

It is possible to declare structure inside the function stack segment or allocate memory dynamically heap segment or it can be even global BSS or data segment. Whatever might be the case, all structure members should reside in the same memory segment because the value for the structure element is fetched by counting the offset of the element from the beginning address of the structure.

Separating out one member alone to data segment defeats the purpose of static variable and it is possible to have an entire structure as static. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

Writing code in comment? Please use ide. Difference Between malloc and calloc with Examples How does free know the size of memory to be deallocated?

What are the default values of static variables in C? Initialization of global and static variables in C Internal static variable vs. Load Comments.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. The pointed dynamic object could be deleted earlier than the program termination, if you don't use the object for the entire duration.

But if that is the case, then why would you own the object through a pointer in static storage? The fact that the memory is technically leaked when the lifetime of the static pointer ends is not a problem because the program is about to end. What you should reconsider is whether you need static storage in the first place.

If you do change your design to use automatic storage instead, then you must be very careful to not leak the memory. Learn more. Asked 3 days ago. Active 3 days ago. Viewed 25 times. Really there is no need to call delete. Yes, it is a memory leak because you don't free the memory but a static variable is only initialized once, meaning you only call new once, and the variable doesn't get destroyed until the end of the program and at that point all the memory gets returned to the OS anyways.

Or use a smart pointer to make sure that it is delete ed explicitly. Although, as NathanOliver has mentioned, it will be deleted ed at the end of the program. Gupta It does not get delete d, which might be an issue for non-trivial types if you rely on the destructor actually doing something important.

For that case OP's question would be much more relevant. Gupta The static object's destructor is called, but I mean the case where the static object is a pointer to a non-trivial-destructible object allocated with new as in OP's example.

That dynamically allocated object's destructor would not be called automatically. Active Oldest Votes.


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