Getting error on Xcode 11 when programming on C++
Please need the urgent support, i am student and programming C++ using xcode 11
getting following error
#include <iostream> . 'iostream' file not found
Question marked as
Xcode is collosal overhead to just to compile a command-line C++ program. Once you have Xcode 11 installed, and have agreed to the extra download dialog, install the Xcode command-line tools:
xcode-select --install
Now, you will have access to clang++ on the command-line and by default, it knows to load the libC++ library if you are not doing any of the later standards (c++17).
To compile the following:
// memoized version of Fibonacci sequence
// Prior results are stored/searched to avoid expensive recalculations
// More: http://xlinux.nist.gov/dads/HTML/memoize.html
// see man clang
// clang++ -Wall -O2 -o fib_memo fib_memo.C -std=c++2a
#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) {
// true if we reach end of array without find success
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;
return 0;
}
Now, using the default C++ library and specifying the iso C++ 2017 spec with amendments and GNU extensions:
clang++ -Wall -O2 -o fib_memo fib_memo.C -std=c++2a
and:
fib_memo
Enter number of terms: 50
12,586,269,025
