What are the default values of static variables in C?
Last Updated :
14 Apr, 2023
In C, if an object that has static storage duration is not initialized explicitly, then: — if it has pointer type, it is initialized to a NULL pointer; — if it has an arithmetic type, it is initialized to (positive or unsigned) zero; — if it is an aggregate, every member is initialized (recursively) according to these rules; — if it is a union, the first named member is initialized (recursively) according to these rules. For example, following program prints: Value of g = 0 Value of gs = 0 Value of s = 0
Example no 1
C
#include <stdio.h>
int g;
static int gs;
int main()
{
static int s;
printf("Value of g = %d", g);
printf("\nValue of gs = %d", gs);
printf("\nValue of s = %d", s);
getchar();
return 0;
}
|
Output
Value of g = 0
Value of gs = 0
Value of s = 0
Example no 2
C
#include <stdio.h>
void print_static_vars(void)
{
static int i = 0;
static float f = 0.0;
static char c = '\0';
i++;
f += 0.1;
c++;
printf("i = %d, f = %f, c = %c\n", i, f, c);
}
int main()
{
print_static_vars();
print_static_vars();
print_static_vars();
return 0;
}
|
Output
i = 1, f = 0.100000, c = ☺
i = 2, f = 0.200000, c = ☻
i = 3, f = 0.300000, c = ♥
Explanation
- In this program, a function print_static_vars is declared that contains three static variables: i, f, and c. The function increments each of these variables and then prints their values.
- The main function calls the print_static_vars function three times. Since the variables are static, their values persist between calls, and their values are updated each time the function is called.
- As you can see, the default value of a static integer variable is 0, the default value of a static float variable is 0.0, and the default value of a static character variable is \0 (the null character).
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