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May 29, 2014 05:27
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Go Golang - pointers exercise, swap x and y
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package main | |
import "fmt" | |
func swap(px, py *int) { | |
tempx := *px | |
tempy := *py | |
*px = tempy | |
*py = tempx | |
} | |
func main() { | |
x := int(1) | |
y := int(2) | |
fmt.Println("x was", x) | |
fmt.Println("y was", y) | |
swap(&x, &y) | |
fmt.Println("x is now", x) | |
fmt.Println("y is now", y) | |
} |
do you know how to write test for this swap function?
hm, i've got it
package main
import (
"testing"
)
type testpair struct {
pairs []int
result []int
}
func TestSwap (t *testing.T) {
tests := []testpair{
{[]int{1,2}, []int{2,1}},
{[]int{5,-1}, []int{-1,5}},
{[]int{123,-123}, []int{-123,123}},
{[]int{0,53535}, []int{53535,0}},
}
for _, tc := range tests {
swap(&tc.pairs[0], &tc.pairs[1])
if tc.pairs[0] != tc.result[0] || tc.pairs[1] != tc.result[1] {
t.Error(
"Expected",
tc.result[0],
tc.result[1],
"but got",
tc.pairs[0],
tc.pairs[1],
)
}
}
}
Approach 1: Using a temporary(temp) variable to store the value of x
package main
import "fmt"
func swap(x *int, y *int) {
temp := *x
*x = *y
*y = temp
}
func main(){
x,y := 5,10
fmt.Println("Before SWAP: ",x,y)
swap(&x,&y)
fmt.Println("After SWAP: ",x, y)
}
/*
Output:
Before SWAP: 5 10
After SWAP: 10 5
*/
Approach 2: No mediators used
package main
import "fmt"
func swap(x *int, y *int) {
*x,*y = *y,*x
}
func main(){
x,y := 5,10
fmt.Println("Before SWAP: ",x,y)
swap(&x,&y)
fmt.Println("After SWAP: ",x, y)
}
/*
Output:
Before SWAP: 5 10
After SWAP: 10 5
*/
Ty, bro for your useful code.
+1 STAR.
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@emirhangl The difference is that in the first approach the
temp
variable is used to store the value ofpx
, and then substitute by the value ofpy
. In the second approach, no intermediary was used.