Prime Number Program for Positive Numbers
This is the prime Number Program for Positive Numbers, if the user enter a negative number then the program asks the user, again and again, to enter the positive number, until the user enters the positive number.
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#include <iostream> using namespace std; int main(){ T4Tutorials: int num; int i; bool isPrime = true; cout << "Enter a positive integer: "; cin >> num; if (num>0) //to ensure the length of number is at least 2 { for(i = 2; i <= num / 2; ++i) { if(num % i == 0) { isPrime = false; break; } } if (isPrime) cout << "This is a prime number"; else cout << "This is not a prime number"; } else { //to ensure that if the length of number is less than 2, then goto T4Tutorials albel (just //below the main function) and again ask the user to enter the number. goto T4Tutorials; } return 0; } |
Flowchart of Sum of Two Prime Numbers – C++ program
C++ program of Sum of Two Prime Numbers
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#include<iostream> using namespace std; int main() { int num, i, j; int f1=1 , f2=1, f3=0; cout<<"Enter a +ve Integar : "; cin>>num; i=3 ; do { f1=1; f2=1; j=2; do { if(i%j==0) { f1=0; j=i; } j=2; do { if((num-i)%j==0) { f2=0; j=num-i; } j++; } while(j<num-i ); if(f1==1 && f2==1) { cout<<num <<" = "<<i<<" + "<<num-i<<endl; f3=1; } j++; } while(j<i); i++; } while(i<=num/2); if(f3==0) { cout<<num<<" can not be expressed as sum of two prime numbers."; } } |
Excercise
Find the possible mistakes in the following Shamil’s Flow Table of the program of Sum of Two Prime Numbers in C++.| Loop 1 | Loop 2 | Loop 3 | If 1 | if 2 | if 3 | If 4 | What line will execute |
| 1 time i=3; | j=2 | j=2 j=3; j=4 j=5 j=6 | False | false | True | False | 1,2,3,4,5,6,7,8,9,10,11,12, 13,14,15,16,17, 22,23,24,25,30,31,32,(23,24,25, 26,27,28,29,30,31,32)4,33,34,35 ,36,37,38,39,40,41,42,43,44,48 |
| 2 time I=4 | j=2 j=3 | J=2 J=3 J=4 J=5 | True | True | False | True | 1,2,3,4,5,6,7,8,9,10,11,12,13, 14,15,16,17,22,23,24,25,30, 31,32,(23,24,25, 26,27,28,29,30,31,32)4,33, 34,35,36,37,38,39,40,41, 42,43, 10,11,12,13,14,15,16,17, 18,19,20,21,22,(23,24,25,26, 27,28,29,30,31,32)2 ,(23,24,25,30,31,32,)2,33,38, 39,40,15,16,17,22,23,24,25, 26,27,28,29,30 ,31,32,(23,24,25,30,31,32,)2, 32,33,38,39,40,41,42, 43,44,45,46,47,48 |
| 3 time I=5; | J=2 | J=2 | False | False | True | False | 1,2,3,4,5,6,7,8,9,10,11, 12,13,14,15,16,17,22,23, 24,25,30,31,32, (23,24,25, 26,27,28,29,30,31,32)4, 33,34,35,36,37,38,39, 40,41,42,43, 10,11,12,13,14,15,16, 17,18,19,20,21,22, (23,24,25,26,27,28,29,30,31,32)2 , (23,24,25,30,31,32,)2, 33,38,39,40,15,16,17,22, 23,24,25,26,27,28,29,30 ,31,32, (23,24,25,30,31,32,)2, 32,33,38,39,40,41,42,43, 10,11,12,13,14,15,16,17,22, (23,24,25,26,27,28,29,30,31,32)3, 33,34,35,36, 37,38,39,40, 15,16,17,22, (23,24,25,26,27,28,29,30,31,32)2, 33,34,35,36, 37,38,39,40, 15,16,17,22, 23, 24,25,26,27,28,29,30,31,32, 33,34,35,36, 37,38,39,40,41,42,43,44,48, |