S3-OOP-Lab
Question 1
❔ Write a program to check whether the given number is prime or not.
Program
#include <iostream>
int main() {
int number;
std::cout << "Enter the number to check :";
std::cin >> number;
for (int i = 2; i < sqrt(number); i++)
if (!(number % i))
return std::cout << "The number is not prime", 0;
std::cout << "The entered number is prime";
return 0;
}
Algorithm
1) start
2) read number
3) Initailize loop variable i=2
4) Check whether the number is less than the root of the entered number
4.1) Check whether the number enter by the user leaves a remainder when it is divided by the loop variable
4.1.1) If the above condition statisfies then we have to assume that the number gets divided and we get the remainder as 0
In such case print number is not prime and exit.
5) Repeat step 3 after increasing the value of loop variable i by 1
6) Print that the numeber is prime.
7) stop
Output
Enter the number to check :123457
The entered number is prime
Process finished with exit code 0
Question 2
❔ Write a program to find gcd of 2 numbers.
Program
#include <iostream>
int main() {
int a, b;
std::cout << "Enter the numbers to find GCD of\n";
std::cin >> a >> b;
if (!((a - b) * a * b))
return std::cout << "GCD = " << (a != 0) * a + (a == 0) * b, 0;
if (std::min(a, b) - a) {
a += b;
b = a - b;
a = a - b;
}
for (int tmp; a; b = tmp) {
tmp = a;
a = b % a;
}
std::cout << "GCD = " << b;
return 0;
}
Algorithm
1) strat
2) read numbers a and b
3) if a=0,b=0, or a=b
3.1) if a = b print a
3.2) if a = 0 print b
3.3) if b=0 print a
4) set minimum as a and maximum as b
5) repeat the steps while a!=0
5.1) temp = a
5.2) a= b%a
5.3) b=temp
6) print b
7) stop
Output
Enter the numbers to find GCD of
123 1234
GCD = 1
Process finished with exit code 0
Question 3
❔ Write a program to find last prime number before the entered input.
Program
#include <iostream>
int main() {
int number;
std::cout << "Enter the number under which you need the prime :";
std::cin >> number;
if (number < 3)
return std::cout << "No primes less than " << number << " found", 0;
int *primes = new int[number/2];
int primes_found = 1;
primes[0] = 2;
for (int i = 3; i < number; i++) {
bool prime = true;
for (int j = 0; j < primes_found; j++)
if (i % primes[j] == 0) {
prime = false;
break;
}
if (prime)
primes[primes_found++] = i;
}
std::cout << "Largest prime < " << number << " = " << primes[primes_found - 1];
delete[] primes;
return 0;
}
Algorithm
Output
Enter the number under which you need the prime :100
Largest prime < 100 = 97
Process finished with exit code 0
