Static storage class - Step-by-Step Execution

Concept Flow - Static storage class

Declare static variable

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Variable stored in static memory

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Function called multiple times

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Variable retains value between calls

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Program ends

Static variables keep their value between function calls by storing data in a fixed memory location.

Execution Sample

C

#include <stdio.h>

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

int main() {
    counter(); counter(); counter();
    return 0;
}

This code shows a static variable 'count' that keeps increasing each time the function is called.

Execution Table

Call Number	count Before Increment	Action	count After Increment	Output
1	0 (initialized)	count++	1	Count: 1
2	1	count++	2	Count: 2
3	2	count++	3	Count: 3
-	-	-	-	Function calls end

💡 After 3 calls, program ends; static variable 'count' retains last value 3.

Variable Tracker

Variable	Start	After Call 1	After Call 2	After Call 3	Final
count	0 (initialized)	1	2	3	3

Key Moments - 2 Insights

Why does 'count' not reset to 0 on each function call?

Because 'count' is declared static, it is initialized only once and keeps its value between calls, as shown in the execution_table rows 1 to 3.

What would happen if 'count' was not static?

Without static, 'count' would be reinitialized to 0 every call, so output would always be 'Count: 1' (see execution_table for static behavior contrast).

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'count' before the second call increments it?

A 0

B 1

C 2

D 3

💡 Hint

Check the 'count Before Increment' column for Call Number 2 in the execution_table.

At which call does 'count' become 3?

A Third call

B Second call

C First call

D Never

💡 Hint

Look at the 'count After Increment' column in the execution_table.

If 'count' was not static, what would be the output on the third call?

A Count: 3

B Count: 2

C Count: 1

D No output

💡 Hint

Refer to key_moments explanation about non-static variable behavior.

Concept Snapshot

Static storage class in C:
- Declared with 'static' keyword inside functions.
- Variable initialized only once.
- Retains value between function calls.
- Stored in static memory, not stack.
- Useful for preserving state without global variables.

Full Transcript

This visual trace shows how a static variable 'count' inside a function keeps its value between calls. Initially, 'count' is set to 0 once. Each time the function runs, 'count' increases by 1 and prints the new value. Unlike normal local variables, 'count' does not reset to 0 on each call. The execution table tracks 'count' before and after increment for each call, showing it grows from 0 to 3 over three calls. Key moments clarify why static variables behave this way and what would happen without 'static'. The quiz tests understanding of variable values at different steps. This helps beginners see how static storage class works step-by-step.