A slice of structures (golang)

// slice_of_structs101.go
//
// convert a csv string into a slice of structures
//
// for imported package info see ...
// http://golang.org/pkg/fmt/
// http://golang.org/pkg/strconv/
// http://golang.org/pkg/strings/
//
// tested with Go version 1.4.2   by vegaseat  27apr2015

package main

import (
	"fmt"
	"strconv"
	"strings"
)

// structure fields match the csv file header
type Billionair struct {
	name   string
	wealth string
	age    string
	source string
}

// show the contents of a slice of strings one line at a time
func show_slice_str(slice []string) {
	for _, item := range slice {
		fmt.Println(item)
	}
}

func main() {
	fmt.Println("convert a csv string into a slice of structures:")

	// could come from a csv file generated by a spreadsheet
	// each line is name,wealth,age,source of a billionair
	csv_str := `Bill Gates,$79.2 billion,59,Microsoft
Carlos Slim,$77.1 billion,75,Telmex and Grupo Carso
Warren Buffett,$72.7 billion,84,Berkshire Hathaway
Amancio Ortega,$64.5 billion,78,Inditex Group
Larry Ellison,$54.3 billion,70,Oracle Corporation
Charles Koch,$42.9 billion,79,Koch Industries
David Koch,$42.9 billion,74,Koch Industries
Christy Walton,$41.7 billion,60,Wal-Mart
Jim Walton,$40.6 billion,66,Wal-Mart
Liliane Bettencourt,$40.1 billion,92,L'Oreal`

	fmt.Println("---------------------------------------------")
	fmt.Println("slice of strings ...")
	// first create a slice of all the lines in the csv_str
	// func Split(s, sep string) []string
	// returns a slice of substrings between sep separators
	slice_str := strings.Split(csv_str, "\n")

	fmt.Printf("%+v\n", slice_str[0])    // test
	fmt.Printf("type = %T\n", slice_str) // type = []string
	show_slice_str(slice_str)

	fmt.Println("---------------------------------------------")
	fmt.Println("slice of structures ...")
	// create pointer to an instance of structure Billionair
	pstb := new(Billionair)
	// now create a slice of structures	using the pointer
	slice_struct := make([]Billionair, len(slice_str))
	for ix, val := range slice_str {
		line := strings.Split(val, ",")
		//fmt.Println(line)
		pstb.name = line[0]
		pstb.wealth = line[1]
		pstb.age = line[2]
		pstb.source = line[3]
		slice_struct[ix] = *pstb
	}

	// %+v adds field names
	fmt.Printf("%+v\n", slice_struct[0])    // test
	fmt.Printf("type = %T\n", slice_struct) // type = []main.Billionair
	// show the contents of the slice of structures
	// range of a slice returns index, value pair
	// index not needed so use blank identifier _
	for _, item := range slice_struct {
		fmt.Println(item)
	}
	fmt.Println("---------------------------------------------")

	// process some data
	age_total := 0
	wealth_total := 0.0
	for _, item := range slice_struct {
		// convert string to integer
		age, err := strconv.Atoi(item.age)
		if err != nil {
			panic(err)
		}
		age_total += age
		// convert the numeric slice [1:5] of the string to a float64
		wealth, err := strconv.ParseFloat(slice_struct[0].wealth[1:5], 64)
		if err != nil {
			panic(err)
		}
		wealth_total += wealth
	}
	average_age := float64(age_total) / float64(len(slice_struct))
	fmt.Printf("average age  = %5.1f\n", average_age)
	fmt.Printf("total wealth = %5.1f billion\n", wealth_total)

	// extra stuff ...
	fmt.Println("---------------------------------------------")
	fmt.Println("extra tests ...")
	fmt.Printf("slice_struct[0].wealth = %v\n", slice_struct[0].wealth)
	// remove $ and billion
	fmt.Printf("slice_struct[0].wealth[1:5] = %v\n",
		slice_struct[0].wealth[1:5])
	// convert to a float
	wealth, err := strconv.ParseFloat(slice_struct[0].wealth[1:5], 64)
	// handle the error if there is one
	if err != nil {
		panic(err)
	}
	fmt.Printf("type = %T  value = %v\n", wealth, wealth)

}

/* result ...
convert a csv string into a slice of structures:
---------------------------------------------
slice of strings ...
Bill Gates,$79.2 billion,59,Microsoft
type = []string
Bill Gates,$79.2 billion,59,Microsoft
Carlos Slim,$77.1 billion,75,Telmex and Grupo Carso
Warren Buffett,$72.7 billion,84,Berkshire Hathaway
Amancio Ortega,$64.5 billion,78,Inditex Group
Larry Ellison,$54.3 billion,70,Oracle Corporation
Charles Koch,$42.9 billion,79,Koch Industries
David Koch,$42.9 billion,74,Koch Industries
Christy Walton,$41.7 billion,60,Wal-Mart
Jim Walton,$40.6 billion,66,Wal-Mart
Liliane Bettencourt,$40.1 billion,92,L'Oreal
---------------------------------------------
slice of structures ...
{name:Bill Gates wealth:$79.2 billion age:59 source:Microsoft}
type = []main.Billionair
{Bill Gates $79.2 billion 59 Microsoft}
{Carlos Slim $77.1 billion 75 Telmex and Grupo Carso}
{Warren Buffett $72.7 billion 84 Berkshire Hathaway}
{Amancio Ortega $64.5 billion 78 Inditex Group}
{Larry Ellison $54.3 billion 70 Oracle Corporation}
{Charles Koch $42.9 billion 79 Koch Industries}
{David Koch $42.9 billion 74 Koch Industries}
{Christy Walton $41.7 billion 60 Wal-Mart}
{Jim Walton $40.6 billion 66 Wal-Mart}
{Liliane Bettencourt $40.1 billion 92 L'Oreal}
---------------------------------------------
average age  =  73.7
total wealth = 792.0 billion
---------------------------------------------
extra tests ...
slice_struct[0].wealth = $79.2 billion
slice_struct[0].wealth[1:5] = 79.2
type = float64  value = 79.2
*/