Calling C function from Julia.md

#include <stdio.h>


int calc(double x[], int len)
{
  for (int i = 0; i < len; i++) {
    x[i] = x[i] * 2;
  }
  return 0;
}

making shared library

gcc -Wall -shared -o calc.so -lm -fPIC test.c

General syntax

ccall((:function_name, "./used_library"), return_type, (argument_type,), argument)

ccall((:calc, "./calc.so"), Void, (Ptr{Cdouble}, Int64), x, length(x))