Initialization of global and static variables in C
Predict the output of following C programs.
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// 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.
