Accessing strings contained in slice - go

Question

I am working on some coding exercises to better understand Go. A given exercise instructs me to create a program that will accept user input as follows:
The first line specifies how many strings will be provided as input on separate lines
The subsequent N lines will each be single strings
I am to output the characters corresponding to even and odd indices of each string separated by a space, and each string on it's separate line.
Example Input:
2
foo_bar
fizz_buzz
Should Output:
fobr o_a
fz_uz izbz
But in my program accessing a slice of strings returns an empty string:
package main
import (
"fmt"
)
func main() {
// read an integer describing how many strings will be input
var num_strings int
fmt.Scan(&num_strings)
// create a slice of strings to hold provided strings
strings := make([]string, num_strings)
// add provided strings to slice
for i := 0; i < num_strings; i++ {
var temp string
fmt.Scan(&temp)
strings = append(strings, temp)
}
// check that strings have been appended
fmt.Println("Strings:", strings)
// check that strings can be accessed
for i := 0; i < num_strings; i++ {
fmt.Println(i, strings[i]) // only i prints, not strings[i]
}
// loop over all strings
for i := 0; i < num_strings; i++ {
// if string index is even print the char
for index, val := range strings[i] {
if index%2 == 0 {
fmt.Print(val)
}
}
fmt.Print(" ")
// if string index is odd print the char
for index, val := range strings[i] {
if index%2 != 0 {
fmt.Print(val)
}
}
// newline for next string
fmt.Print("\n")
}
}
2
foo_bar
fizz_buzz
Strings: [ foo_bar fizz_buzz]
0
1

Answer 1

Because when you make your strings slice, you're creating a slice with both a capacity and length of n. So when you append to it, you're increasing the length of the slice:
Change this bit of code:
// create a slice of strings to hold provided strings
strings := make([]string, num_strings)
// add provided strings to slice
for i := 0; i < num_strings; i++ {
var temp string
fmt.Scan(&temp)
strings = append(strings, temp)
}
to either:
// create a slice of strings to hold provided strings
strings := []{}
// add provided strings to slice
for i := 0; i < num_strings; i++ {
var temp string
fmt.Scan(&temp)
strings = append(strings, temp)
}
Or
// create a slice of strings to hold provided strings
strings := make([]string, num_strings)
// add provided strings to slice
for i := 0; i < num_strings; i++ {
var temp string
fmt.Scan(&temp)
strings[i] = temp
}
And you should be good.