1. Introduction to Computer Algorithmics and Programming Ceng 113
Variables and Operators in C

2. Exercise - 1 Top-Down, Stepwise Refinement
Begin with a pseudocode representation of the top:
Check the primality of given number.
Divide top into smaller tasks and list them in order:
Initialize variables. Input number and try to find a divisor for this number. (The divisor should be different than the given number). Check status and print the primality decision for the given number.

3. Exercise - 1 Top-Down, Stepwise Refinement
Refine the initialization phase from Initialize variables to:
Initialize counter to zero Initialize quotient to zero
Refine Input number and try to find and divisor for this number. (The divisor should be different one and the given number),
Input the number
divider is equal to (number/2 +1)‏
While the divider greater than 1 and (quotient*divider) not equal to number
quotient = number / divider
divider = divider – 1

4. Exercise - 1 Top-Down, Stepwise Refinement
Refine Check the status and print the primality decision for the given number to
if divider equal to one
print “The given number is prime”
else print “The given number is not prime”

5. // Subject: Check the primality of given number.
// Initialize counter to zero
// Initialize quotient to zero
// Input the number
// divider is equal to (number/2 + 1)‏
// While (divider greater than 1) and (quotient*divider is not equal to number)‏
// divider = divider - 1
// quotient = number / divider
// if divider equal to one
// print "The given number is prime"
// else print "The given number is not prime"
# include <stdio.h>
int main ()‏
{ int counter=0, quotient=0, number, divider;
printf("Enter an integer number:");
scanf("%d", &number);
divider = number/2 + 1;
while ((divider>1) && ((quotient*divider) != number))‏
{ divider = divider - 1;
quotient = number / divider; }
if (divider == 1) printf("The number %d is prime.\n", number);
else printf("The number %d is not prime. \n", number);
return 0;

6. Exercise # 3 Write a program to calculate the value of factorials.
1.Take the values for upper and lower limits from the screen between 0 and 10 then,
2. display the factorial values for the each number.

7. Exercise #3 Calculate the factorial value of a given integer.
Pre : Take the integer value. The value of this number should be between 0 and 10.
Post: Calculate the factorial value of the given number. (n!= n)
Return: Factorial value should be return.
1. number, sayac = 0, factorial = 1
2. Loop number<0 OR number >10
2.1 Input the integer value to number variable.
3. Sayac = number
4. Loop sayac != 0
4.1 factorial = factorial.sayac
4.2 sayac = sayac – 1
5. Return (factorial)‏

8. Exercise #3 # include <stdio.h> int main ()‏
{ int number=0, factorial=1;
do {
printf(“\n 0-10 aralığında bir tamsayı giriniz :”);
scanf(“%d”, &number);
} while ((number<0) || (number>10));
while (number >0) {
factorial = factorial * number;
number = number – 1; }
printf(“\n Factorial : %d”, factorial);
Main
function

9. Exercise #3 # include <stdio.h> int factor(int x); int main ()‏
{ int number;
do {
printf(“\n 0-10 aralığında bir tamsayı giriniz :”);
scanf(“%d”, &number);
} while ((number<0) || (number>10));
printf(“\n Factorial : %d”, factor(number)); }
int factor(int x) {
int factorial = 1;
while (x >0) {
factorial = factorial * x;
x = x – 1;
return(factorial);
Main
function
Factorial
function

10. Exercise #4 #include "stdio.h" int count; /* count is global */
void func1(void);
void func2(void);
void main(void)‏
{ count = 100;
func1(); }
void func1(void)‏
{ int temp;
temp = count;
func2();
printf("\n count is %d \n", count);
void func2(void)‏
{ int count;
for (count=1; count<10; count++)‏
printf(“*");