Skip to content
Related Articles

Related Articles

Improve Article

Initialization of global and static variables in C

  • Difficulty Level : Medium
  • Last Updated : 08 May, 2017

Predict the output of following C programs.

Take a step-up from those "Hello World" programs. Learn to implement data structures like Heap, Stacks, Linked List and many more! Check out our Data Structures in C course to start learning today.




// PROGRAM 1
#include <stdio.h>
#include <stdlib.h>
  
int main(void)
{
   static int *p = (int*)malloc(sizeof(p));
   *p = 10;
   printf("%d", *p);
}




// PROGRAM 2
#include <stdio.h>
#include <stdlib.h>
int *p = (int*)malloc(sizeof(p));
  
int main(void)
{
    *p = 10;
    printf("%d", *p);
}

Both of the above programs don’t compile in C. We get the following compiler error in C.

error: initializer element is not constant

In C, static and global variables are initialized by the compiler itself. Therefore, they must be initialized with a constant value.

Note that the above programs compile and run fine in C++, and produce the output as 10.

As an exercise, predict the output of following program in both C and C++.




#include <stdio.h>
int fun(int x)
{
    return (x+5);
}
  
int y = fun(20);
  
int main()
{
    printf("%d ", y);
}

This article is contributed by Shankar Shastri. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.




My Personal Notes arrow_drop_up
Recommended Articles
Page :