Function parameters - Step-by-Step Execution

Concept Flow - Function parameters

Define function with parameters

↓

Call function with arguments

↓

Pass arguments to parameters

↓

Execute function body using parameters

↓

Return result or finish

↓

Back to caller

This flow shows how a function is defined with parameters, called with arguments, and how those arguments are passed to parameters for use inside the function.

Execution Sample

C

int add(int x, int y) {
    return x + y;
}

int main() {
    int result = add(3, 4);
    return 0;
}

This code defines a function 'add' with two parameters and calls it with arguments 3 and 4, returning their sum.

Execution Table

Step	Action	Parameters	Arguments Passed	Result/Output
1	Define function 'add' with parameters x and y	x, y	N/A	Function ready
2	Call 'add' with arguments 3 and 4	x, y	3, 4	Call initiated
3	Pass arguments to parameters	x=3, y=4	3, 4	Parameters set
4	Execute function body: return x + y	x=3, y=4	3, 4	7
5	Return result 7 to caller	x, y	3, 4	7
6	Store result in 'result' variable	N/A	N/A	result = 7
7	End program	N/A	N/A	Program ends

💡 Function completes after returning the sum; main ends after storing result.

Variable Tracker

Variable	Start	After call	After return	Final
x	undefined	3	3	undefined after function ends
y	undefined	4	4	undefined after function ends
result	undefined	undefined	7	7

Key Moments - 2 Insights

Why do parameters x and y have values only inside the function?

Parameters x and y get their values when the function is called (see step 3 in execution_table). Outside the function, they don't exist, so they are undefined there.

What happens if we call the function with different arguments?

The arguments passed replace the parameters' values during that call (step 3). So the function uses those new values each time it runs.

Visual Quiz - 3 Questions

Look at the execution_table at step 4, what is the value of x and y inside the function?

A x=3, y=4

B x=0, y=0

C x and y are undefined

D x=4, y=3

💡 Hint

Check the 'Parameters' column at step 4 in execution_table.

At which step does the function return the sum of the parameters?

A Step 2

B Step 4

C Step 6

D Step 7

💡 Hint

Look for the step where the action is 'Execute function body: return x + y'.

If we change the call to add(5, 6), what will be the value of 'result' after the call?

A 7

B undefined

C 11

D 0

💡 Hint

Refer to variable_tracker and understand how arguments affect parameters and result.

Concept Snapshot

Function parameters in C:
- Defined in function signature (e.g., int add(int x, int y))
- Receive values from arguments when function is called
- Parameters exist only during function execution
- Used inside function body to perform tasks
- Return values can be stored or used by caller

Full Transcript

This visual trace shows how function parameters work in C. First, a function is defined with parameters. When the function is called, arguments are passed to these parameters. Inside the function, parameters hold the argument values and are used to compute results. After the function finishes, parameters go out of scope. The result can be returned and stored by the caller. This helps understand how data moves into and out of functions.