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Q1_alter.c
Q1_alter.c
 
 
Q2_divide_remain.c
Q2_divide_remain.c
 
 
Q3_powered_sums.c
Q3_powered_sums.c
 
 
Q4_complex_power.c
Q4_complex_power.c
 
 
README.md
README.md
 
 

README.md

Week 8 Notes

Functions - Call by Reference - Pointers

Function Syntax


Swap - Call by Value (Scope of Variables)

#include <stdio.h>
 
/* function declaration */
void swap(int a, int b);

/* function definition to swap the values */
void swap(int a, int b) {

   int temp;

   temp = a; /* save the value of a */
   a = b;    /* put b into a */
   b = temp; /* put temp into b */
}
 
int main () {

   /* local variable definition */
   int a = 100;
   int b = 200;
 
   printf("Before swap, value of a : %d\n", a );
   printf("Before swap, value of b : %d\n", b );
 
   /* calling a function to swap the values */
   swap(a, b);
 
   printf("After swap, value of a : %d\n", a );
   printf("After swap, value of b : %d\n", b );
 
   return 0;
}


Pointers

#include <stdio.h>

int main () {
	int *p;
	int c;

	p = &c;
	c = 4;

	*p = 21;

	int d = 34;

	p = &d;

	printf("%d")

	return 0;
}


Line by line outputs

#include <stdio.h>

int main () {
	int *p;
	int c;
	
	printf("int *p, c\n");
	printf("&p: %p  -  p: %p\n",&p ,p);
	printf("&c: %p  -  c: %d\n",&c ,c);
    printf("\n\n");

	p = &c;
	c = 4;
	
	printf("p = &c;\nc = 4;\n");
	printf("&p: %p  -  p: %p  -  *p: %d\n",&p ,p, *p);
	printf("&c: %p  -  c: %d\n",&c ,c);
    printf("\n\n");

	*p = 21;
	
	printf("*p = 21;\n");
	printf("&p: %p  -  p: %p  -  *p: %d\n",&p ,p, *p);
	printf("&c: %p  -  c: %d\n",&c ,c);
    printf("\n\n");

	int d = 34;
	
	p = &d;

    printf("int d = 34;\np = &d;\n");
	printf("&p: %p  -  p: %p  -  *p: %d\n",&p ,p, *p);
	printf("&c: %p  -  c: %d\n",&c ,c);
	printf("&d: %p  -  d: %d\n",&d ,d);

	return 0;
}

Side note: Two different ways to define a pointer and then assing an address to it.

int n = 5;
int *p;
p = &n;
int n = 5;
int *p = &n;

Swap - Call by Reference

#include <stdio.h>
 
/* function declaration */
void swap(int *a, int *b);

/* function definition to swap the values */
void swap(int *a, int *b) {
    int temp;

    temp = *a; /* save the value of *a */
    *a = *b;    /* put *b into *a */
    *b = temp; /* put temp into *b */
}
 
int main () {
    /* local variable definition */
    int a = 100;
    int b = 200;

    printf("Before swap, value of a : %d\n", a );
    printf("Before swap, value of b : %d\n", b );

    /* calling a function to swap the values */
    swap(&a, &b);

    printf("After swap, value of a : %d\n", a );
    printf("After swap, value of b : %d\n", b );

    return 0;
}


Question 1 - Number Alteration

In the main function, one integer number and a char are read from the user into the variables x and c respectively. Complete the program by writing the function alter.

alter function takes one integer pointer (address of an integer) and one char variable as parameters. Function does the following operations:

  • If char parameter is 'i', then increase the integer pointer parameter by one.
  • If char parameter is 'd', then decrease the integer pointer parameter by one.
  • If char parameter is 's', then assign the square of the integer pointer parameter to itself.
  • Otherwise, do not change anything.

In the main function send variables x and c to the alter function and then print x in the main function.

INPUT OUTPUT
22 i 23
-4 d -5
20 s 400
20 j 20 

#include <stdio.h>

// DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

// DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE

int main()
{
    int x;
    char c;
    
    scanf("%d %c", &x, &c);
    
    alter(
    // DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

    // DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE
        );
        
    printf("%d", x);
    return 0;
}

Question 2 - Divide and Remain Still

Write a function named divideWithRemainder which takes two integer (number, divisor) and two integer pointer variables (*result, *remainder) as parameters:

This function should divide the number by divisor, then store the result in the parameter *result, and store the remainder in the parameter *remainder.

INPUT OUTPUT
8 3 2 2
27 4 6 3
10 2 5 0 

#include <stdio.h>

// DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

// DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE

int main()
{
    int n, d, res, rem;
    
    scanf("%d %d", &n, &d);
    
    divideWithRemainder(
    // DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

    // DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE
        );
        
    printf("%d %d", res, rem);
    return 0;
}

Question 3 - Powered Sums

In the main function, two integer numbers are read from the user into the variables a and b respectively. Complete the program by writing two functions named sums and powered.

sums takes two integers (a and b) and an integer pointer (*sum). The function should store the sum of these two integers in *sum pointer.

powered takes three integers (sum, a and b) and two integer pointers (*sum_p1 and *sum_p2). The function should store the $a^{th}$ power of the sum in *sum_p1 and $b^{th}$ power of the sum in *sum_p2.

Output:

First Line: Sum of two numbers

Second Line: $a^{th}$ power of the a+b and $b^{th}$ power of the a+b

INPUT OUTPUT
6 1 7
117649 7
4 4 8
4096 4096
5 0 5
3125 1		 

#include <stdio.h>

// DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

// DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE

int main(){
	int a, b;
	scanf("%d %d",&a,&b);

	int sum;
	sums(
		// DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

		// DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE
	);
	printf("%d\n",sum);

	int sum_p1,sum_p2;
	powered(
		// DO_NOT_EDIT_ANYTHING_ABOVE_THIS_LINE

		// DO_NOT_EDIT_ANYTHING_BELOW_THIS_LINE);
	);
	printf("%d %d", sum_p1, sum_p2);

	TC_END;
    return 0;
}

Question 4 - Complex Powers (Old Midterm Question)

  • Think about how we write the regular power.

Complex Powers