Hey I am trying to create a simple scalar vector for my program.
I was starting with a simple variable and incrementing it to make it a 32 by 1 size vector matrix.
var x []int
for i := 0; i < 32 ; i++{
x[i] = i + 1
}
Simple enough but when trying to compile this I get this error.
panic: runtime error: index out of range
goroutine 1 [running]:
main.main()
/Users/jeanmac/go/src/matrices/main.go:69 +0x7d
Process finished with exit code 2
Not sure why. FYI Line 69 refers to x[i] = i + 1. When trying to assign x[i] I receive the following warning.
Reports indexing of nil map or slice that may lead to runtime panic.
Not sure why this seems to be happening.
Allocate the slice. For example,
package main
import "fmt"
func main() {
x := make([]int, 32)
for i := range x {
x[i] = i + 1
}
fmt.Println(x == nil, len(x), cap(x), x)
}
Playground: https://play.golang.org/p/UVrUAZHtTw-
Output:
false 32 32 [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32]
In your example, you have a zero-value (nil) slice which has length 0. Therefore, x[i] or x[0] is panic: runtime error: index out of range.
package main
import "fmt"
func main() {
var x []int
fmt.Println(x == nil, len(x), cap(x), x)
for i := 0; i < 32; i++ {
x[i] = i + 1
}
}
Playground: https://play.golang.org/p/3hG5FpV3_dC
Output:
true 0 0 []
panic: runtime error: index out of range
main.go:9
References: