Why am I getting the 'expected expression' error?

I'm guessing that the line before the "for" line:

cout <<"Fibonacci Series: " << firstTerm << " + " << secondTerm <<

is not properly terminated, it looks like a ";" is missing and that you have a "<<" to much.

The compiler is basically seeing something like:

cout <<"Fibonacci Series: " << firstTerm << " + " << secondTerm << for (int i = 1; i <= n-2; ++i) { .... }

Hokanst is correct.

The following change:

cout <<"Fibonacci Series: " << firstTerm << " + " << secondTerm;

enables a clean compile with clang++, and correct execution.

Another (faster) variation on Fibonacci that uses memoization techniques to avoid costly recalculations. This was translated from an existing Python solution.

// memoized version of Fibonacci sequence

// Prior results are stored/searched to avoid expensive recalculations

// More: http://xlinux.nist.gov/dads/HTML/memoize.html

// clang++ -Wall -O2 -o fib_memo fib_memo.C -std=c++11 -stdlib=libc++

#include <iostream>

#include <locale>

#include <map>

using namespace std;

// key/value pair associative array

std::map<u_long, u_long> alreadyknown;

u_long n=0, newvalue=0;

u_long fib(u_long n) {

// not found is a true condition here

if (alreadyknown.find(n) == alreadyknown.end()) {

newvalue = fib(n-1) + fib(n-2);

alreadyknown[n] = newvalue;

}

return alreadyknown[n];

}

int main(int argc, char* argv[]) {

// initialize memoization key/value pair

alreadyknown[0] = 0;

alreadyknown[1] = 1;

cout<<"Enter the number of terms: ";

cin>>n;

std::locale mylocale("");

std::cout.imbue(mylocale); // use locale number formatting style

cout<<fib(n) << endl;

return0;

}