# Solution: Reverse Polish Calculator

examples/rpc/rpc.go
```package main

import (
"fmt"
"log"
"os"
"strconv"
"strings"
)

func main() {
if len(os.Args) != 2 {
fmt.Printf("Usage: %s EXPRESSION (put the whole thing in quotes)\n", os.Args[0])
os.Exit(1)
}
expression := os.Args[1]
//fmt.Println(expression)
parts := strings.Fields(expression)
//fmt.Println(parts)
//fmt.Println(len(parts))
result := rpc(parts)
fmt.Println(result)

}

func rpc(parts []string) float64 {
stack := []float64{}
for _, value := range parts {
//fmt.Println(value)
if value == "=" {
log.Println("=")
if len(stack) == 0 {
panic("Operator = received and we have no value to print")
}
a := stack[len(stack)-1]
stack = stack[:len(stack)-1]
return a
}
if value == "+" || value == "*" || value == "-" || value == "/" {
log.Println(value)
if len(stack) < 2 {
}
b := stack[len(stack)-1]
a := stack[len(stack)-2]
var c float64
switch value {
case "+":
c = a + b
case "-":
c = a - b
case "*":
c = a * b
case "/":
c = a / b
default:
panic("How could this happen?")
}

stack = stack[:len(stack)-2]
stack = append(stack, c)
continue
}
number, err := strconv.ParseFloat(value, 64)
if err != nil {
panic(fmt.Sprintf("Unhandled value %v", value))
}
log.Println(number)
stack = append(stack, number)
}
return 0
}

```