added examples folder

Author: Pramod-Devireddy

examples/example-01.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/Pramod-Devireddy/go-exprtk"
+)
+
+func main() {
+	// Create a new exprtk instance
+	exprtkObj := exprtk.NewExprtk()
+
+	// Set the expression
+	exprtkObj.SetExpression("(x + 2)*(y-2)")
+
+	// Add variables of expression
+	exprtkObj.AddDoubleVariable("x")
+	exprtkObj.AddDoubleVariable("y")
+
+	// Compile the expression after expression and variables declaration
+	exprtkObj.CompileExpression()
+
+	// Set values for the variables
+	exprtkObj.SetDoubleVariableValue("x", 18)
+	exprtkObj.SetDoubleVariableValue("y", 32)
+
+	// Get the evaluated value
+	fmt.Println(exprtkObj.GetEvaluatedValue())
+
+	// Modify values for the variables
+	exprtkObj.SetDoubleVariableValue("y", 42)
+
+	// Get re-evaluated value
+	fmt.Println(exprtkObj.GetEvaluatedValue())
+}

exprtk.go

@@ -4,7 +4,9 @@ package exprtk
 // #cgo LDFLAGS: -L.
 // #include "exprtkwrapper.h"
 import "C"
-import "fmt"
+import (
+	"errors"
+)
 
 // GoExprtk ...Exprtk Structure
 type GoExprtk struct {
@@ -60,13 +62,12 @@ func (obj GoExprtk) SetVectorVariableValue(varName string, val []float64) {
 }
 
 // CompileExpression ... Compiles the Expression
-func (obj GoExprtk) CompileExpression() {
+func (obj GoExprtk) CompileExpression() error {
 	value := C.compileExpression(obj.exprtk)
 	if value == 0 {
-		fmt.Println("Equation didn't compile")
-	} else {
-		fmt.Println("Equation Compiled")
+		return errors.New("Failed to compile the expression")
 	}
+	return nil
 }
 
 // GetEvaluatedValue ... Returns the evaluated value