// use dynamic loader to lookup function by name and return pointer-to-function
// compile with -rdynamic -ldl -lm
//
// R. Perry, March 2019
//
#include <stdio.h>

#include "lookup.h"

double sqr( double x) { return x*x; } // square

void try( const char *name) // try calling a function
{
  Func g = lookup( name);

  if(g) { double x = 2; printf("%s(%g) = %g\n", name, x, g(x) ); }
}

int main( void)
{
  try( "sqr");

  try( "abc123");

  try( "sqrt");
}

/* sample output, linked with math library, -lm

 sqr(2) = 4
 dlsym: ./main: undefined symbol: abc123
 sqrt(2) = 1.41421

not linked with math library:

 sqr(2) = 4
 dlsym: ./main: undefined symbol: abc123
 dlsym: ./main: undefined symbol: sqrt

*/