Static storage class - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of static variable in function

What is the output of this C program?

C

#include <stdio.h>

void counter() {
    static int count = 0;
    count++;
    printf("%d ", count);
}

int main() {
    for(int i = 0; i < 3; i++) {
        counter();
    }
    return 0;
}

A 1 2 3

B 0 1 2

C 1 1 1

D 3 3 3

💡 Hint

Remember that static variables inside functions keep their value between calls.

The static variable 'count' is initialized only once and retains its value between function calls, so it increments each time the function is called.

❓ Predict Output

intermediate

Static variable scope in multiple files

Given two files, what will be the output when compiled and run together? File1.c: #include static int x = 5; void printX() { printf("%d\n", x); } File2.c: extern void printX(); int main() { printX(); return 0; }

A 5

B 0

C Compilation error

D Undefined reference error

💡 Hint

Static variables have internal linkage, but functions can access them within the same file.

The static variable 'x' is only visible inside File1.c, but the function printX() can access it and print 5. The main calls printX(), so output is 5.

🔧 Debug

advanced

Why does this static variable reset unexpectedly?

Consider this code snippet: #include void func() { static int val = 10; printf("%d ", val); val = 5; } int main() { func(); func(); return 0; } What is the output and why?

A Compilation error

B 10 10

C 5 5

D 10 5

💡 Hint

Static variables keep their value between calls, but you are changing it inside the function.

The static variable 'val' is initialized once to 10. The first call prints 10 and sets val to 5. The second call prints 5 because val retains the changed value.

📝 Syntax

advanced

Identify the syntax error with static variable usage

Which option contains a syntax error related to static variable declaration?

C

void example() {
    static int a = 0;
    a++;
}

A static int a = 0; inside a function is valid

B static int a = 0; outside any function is valid

C static int a = 0 inside a function without semicolon is invalid

D static int a; outside any function is invalid

💡 Hint

Look for missing semicolons in the declarations described in the options.

Option C describes 'static int a = 0 inside a function without semicolon', which lacks a semicolon after the declaration and is a syntax error. The other options describe valid syntax.

🚀 Application

expert

How many times is the static variable initialized?

Analyze this code: #include void test() { static int x = 0; printf("%d ", x); x++; } int main() { for(int i = 0; i < 4; i++) { test(); } return 0; } How many times is the static variable 'x' initialized during the program execution?

A Every time test() is called

B Once, before the first call to test()

C Once, at the start of main()

D Never, it is uninitialized

💡 Hint

Static variables inside functions are initialized only once, not every call.

The static variable 'x' inside test() is initialized only once before the first call to test(). It keeps its value between calls.