### 25.7.1 Using giac inside a C++ program

To use giac inside of a C++ program, put

#include <giac/giac.h>

at the beginning of the file. To compile the file, use

c++ -g progname.cc -lgiac -lgmp

After compiling, there will be a file a.out which can be run with the command

./a.out

As an example, put the following program in a file named pgcd.cc.

#include <giac/config.h> #include <giac/giac.h> using namespace std; using namespace giac; gen pgcd(gen a,gen b) { gen q,r; for (;b!=0;) { r=irem(a,b,q); a=b; b=r; } return a; } int main() { cout << "Enter 2 integers "; gen a,b; cin >> a >> b; cout << pgcd(a,b) << endl; return 0; }

After compiling this with

c++ -g pgcd.cc -lgiac -lgmp

and running it with

./a.out

a prompt will appear:

Enter 2 integers

After entering two integers, such as

Enter 2 integers 30 36

the result will appear:

6