Example1

Purpose

C++ code illustrating using C++ on the FASRC cluster. sum.cpp computes integer sum from 1 to N (N is read from command line). Since this code reads an input from the command line, it cannot be run as a batch job and only as an interactive job.

Contents

• sum.cpp: c++ source code

C++ code

//==========================================================
// Program: sum.cpp
//          Computes integer sum from 1 to N where N
//          is a number read from the command line
//==========================================================
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

// Main program.............................................
int main(){
  int i;
  int n;
  int k;
  string mystr;
  cout << "Enter an integer: ";
  getline(cin,mystr);
  stringstream(mystr) >> n;
  k = 0;
  for ( i = 0; i <= n; i++ ){
    k = k + i;
  }
  cout << "Sum of integers from 1 to " << n << " is " <<
    k << '\n';
  return 0;
}

Compile

We recommend compiling on a compute node. Request an interactive job to use a compute node, e.g.,

salloc --partition test --time 00:30:00 -c 2 --mem-per-cpu 2G

• Intel compilers, e.g.,

module load intel
icpc -O2 -o sum.x sum.cpp  # for intel version < 23.2, use `icpc`
icpx -O2 -o sum.x sum.cpp  # for intel version >= 23.2, use `icpx`.

• GNU compilers, e.g.,

module load gcc
g++ -O2 -o sum.x sum.cpp

Run interactive code

On a compute node

./sum.x

Example output

Enter an integer: 7
Sum of integers from 1 to 7 is 28