Question

PART II: DISCOVERY ACTIVITIES

1. Using your text book, or an Internet search (you can ask your TA) or simply by experimenting with C, explain in a few sentences the difference between arguments and parameters and the purpose of the return statement in functions.
2. Using your text book, or an Internet search (you can ask your TA) or simply by experimenting with C, explain in a few sentences the difference between the * and the & operators (* related to pointers, not the multiplication operator).

Answer 1

1. Difference between arguments and parameters​​​​​​​​​​​​​​​​​​​​​

The terms arguments and parameters means the same for noobs, but are very different in general.

PARAMETERS:- A parameter is a data variable having local or global scope in a program that is used to store the data of various types(int, float, char, etc..) during the execution of a program.

Example:- A simple program to add two no.s has only three parameters involved in its execution. Two parameters store the no.s whose sum is to be calculated while the third parameter is used for storing the calculated sum.

void add( )

{

int a=10,b=15,int sum=0; //Parameters

sum=a+b;

printf("%d",sum);

}

ARGUMENTS:- An argument is a data variable that is used to exchange information between subroutines or invoke a subroutine during function call.

Example:- Continuing with the above example, suppose if the above program to add two no.s takes input from user in a different function and the procedure to add the two no.s is stored in a different function, so in order to calculate the sum of two no.s we need to pass the two no.s to our sum function. When the sum function is invoked and the two no.s are passed during the function call, these will act as arguments for the sum function.

//function to add two no.s

void add(int a, int b) //a and b are formal arguments as their values will be exchanged from the main() function.

{ int n1,n2,sum=0; // n1 and n2 are parameters

n1=a;

n2=b;

sum=n1+n2;

printf("%d",sum);

}

//function to take inputs

void main()

{int a,b;

scanf("%d%d",&a,&b); //taking values of a and b from the user

add(a,b); // called the add function to calculate sum.

}

2. Difference between * and & operators

* operator(Indirection Operator):- This operator is used to declare pointers. Pointers are the variables that store addresses of the other variables. It is also known as dereferencing operator.

It is also used to print the value stored at an address of a variable.

& Operator(address-of-operator):- This operator is generally used to refer to the memory location where the data is actually stored. It is used when we perform parameter passing by reference.

Example:- Consider the following program:

#include<studio.h>

void main( )

{

int a=5;

int *p; //pointer for an int type variable declared using * operator

p=&a; //referencing the variable a to pointer p using the & operator

printf("%d",p) //It will print the address of variable a contained in variable p.

printf("%d",*p) //It will print the value stored at the address contained in variable p i.e. 5

}

Hope this helps :)