Print prime numbers in a given range using C++ STL


It is the program to print prime numbers in a given range.

Algorithms

Begin
   Declare a user define datatype stl.
   Declare a vector number to the stl datatype.
   Declare variable a to the stl datatype.
   Declare vector Prime_Number to the Boolean datatype.
      Prime_Number[0] = false.
      Prime_Number[1] = false.
   Declare b to the integer datatype.
      Initialize b = sqrt(a).
   for (stl pr=2; pr<=b; pr++)
      if (Prime_Number[pr]) then
         for (stl i=pr*2; i<=a; i += pr)
            Prime_Number[i] = false.
   Declare result to the vector type.
   for (int i=0;i<a;i++)
      if (Prime_Number[i]) then
         result.push_back(i).
      return result.
End
Begin
   Declare function remove_zero() to the Boolean type.
   Declare i to the stl datatype.
   Return i = 0.
End
Begin
   Declare a vector Number_Range to the stl datatype.
   Declare First_Num, Last_Num to the stl datatype.
   Pass them as parameter.
   Declare two vector s1 and s2 to the stl datatype.
      Initialize s1 = number(First_Num) to find primes from o to First_Num.
      Initialize s2 = number(Last_Num) to find primes from o to Last_Num.
   Declare vector result(Last_Num-First_Num) to the stl datatype.
   Call set_difference(s2.begin(), s2.end(), s1.begin(), s2.end(), result.begin()) to find set difference of two vectors.
   Declare an iterator itr to the vector type.
      Initialize itr = remove_if(result.begin(),result.end(),remove_zero) to remove extra zeros.
   Call resize (itr-result.begin()) to resize the result.
   Return result.
   Declare First_Num, Last_Num to the stl datatype.
      Initialize First_Num = 20, Last_Num = 50.
   Declare a vector result to the stl datatype.
      Initialize result = Number_Range(First_Num,Last_Num).
   Print "The Prime Numbers from 20 to 50 are: “
   for (auto i:result)
      Print the values of i.
End.

Example

 Live Demo

#include<bits/stdc++.h>
using namespace std;
typedef unsigned long long int stl;
vector<stl> number(stl a) {
   vector<bool> Prime_Number(a+1,true);
   Prime_Number[0] = false;
   Prime_Number[1] = false;
   int b = sqrt(a);
   for (stl pr=2; pr<=b; pr++) {
      if (Prime_Number[pr]) {
         for (stl i=pr*2; i<=a; i += pr)
            Prime_Number[i] = false;
      }
   }
   vector<stl> result;
   for (int i=0;i<a;i++)
      if (Prime_Number[i])
         result.push_back(i);
   return result;
}
bool remove_zero(stl i) {     // Used to remove zeros from a vector
   return i == 0;
}
vector<stl> Number_Range(stl First_Num,stl Last_Num) {
   vector<stl> s1 = number(First_Num); // find primes from o to First_Num
   vector<stl> s2 = number(Last_Num); // find primes from o to Last_Num
   vector<stl> result(Last_Num-First_Num);
   set_difference(s2.begin(), s2.end(), s1.begin(), s2.end(), result.begin()); // find set //difference of two vectors
   vector<stl>::iterator itr = remove_if(result.begin(),result.end(),remove_zero); //remove extra zeros.
   result.resize(itr-result.begin());
   return result;
}
int main(void) {
   stl First_Num = 20, Last_Num = 50;
   vector<stl> result = Number_Range(First_Num,Last_Num);
   cout<<"The Prime Numbers from "<<First_Num<<" to "<<Last_Num<< " are: ";
   for (auto i:result)
      cout<<i<<' ';
   return 0;
}

Output

The Prime Numbers from 20 to 50 are: 23 29 31 37 41 43 47
raja
Published on 18-Jun-2019 16:36:21
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