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Akash Halder Tutorials

Prameters

Actual Parameters: Arguments passed to a function.

  • They exist in the calling function (where the function is called).
  • They supply input data to the function.
  • They can be constants, variables, or expressions.

Formal Parameters: Parameters received by the function.

  • They exist inside the function (local to the function).
  • They store copies or references of actual parameters depending on the method of passing (value or reference).
  • They terminate when the function ends.
#include <stdio.h>


void display(int x) {   // x is formal parameter
printf("Value: %d\n", x);
}


int main() {
int num = 10;
display(num);  // num is the actual parameter
return 0;
}

Actual Argument:

  • Definition: It refers to the expression used within the function call to pass a value or reference.
  • Usage: Act as input values during function execution.
  • Example: In foo(x), x is the actual argument.

Formal Argument:

  • Definition: It refers to the parameters declared in the function definition.
  • Usage: Serve as placeholders for receiving values from actual arguments.
  • Example: In void foo(int y), y is the formal argument.

Call by Value:

  • Copies the value of actual parameter
  • Does not affect the actual parameter
  • Default method in C.
#include <stdio.h>


void swap(int x, int y)
{
int temp;
temp = x;
x = y;
y = temp;
printf("\nInside swap function:");
printf("\nValue of x: %d", x);
printf("\nValue of y: %d", y);
}


int main()
{
int r = 10, v = 20;
swap(r, v);  // passing values (call by value)
printf("\n\nInside main function:");
printf("\nValue of r: %d", r);
printf("\nValue of v: %d", v);


return 0;
}

Call by Reference:

  • Passes the address of actual parameter
  • Changes to formal parameter affect actual parameter
  • Implemented using pointers in C.
#include <stdio.h>
void changeValue(int* address)
{
*address = 36979898;
}


int main()
{
int a = 34, b =56;
printf("The value of a now is %d\n", a);
changeValue(&a);
printf("The value of a now is %d\n", a);
return 0;
}

Example

Section titled “Example”
#include <stdio.h>
void greetUser(char name[], int age) {
printf("Hello %s! You are %d years old.\n", name, age);
}
int main() {
greetUser("Akash", 25);
greetUser("Shruti", 30);
return 0;
}