m := map[string]int{"one":1,"two":2,"three":3} m1 := map[string]int{} m1["one"] = 1 m2 := make(map[string]int, 10 /*initial capacity*/)
在访问的key不存在时,仍会返回零值,不能通过返回nil来判断元素是否存在
func testaccessnotexistingkey(t *testing.t) { m1 := map[int]int{} t.log(m1[1]) m1[2] = 0 t.log(m1[2]) m1[3] = 0 //可以注释此行代码查看运行结果 if v,ok:=m1[3];ok{ t.logf("key 3's value is %d",v) }else { t.log("key 3 is not existing.") } }
输出
=== run testaccessnotexistingkey --- pass: testaccessnotexistingkey (0.00s) map_test.go:20: 0 map_test.go:22: 0 map_test.go:25: key 3's value is 0 pass process finished with exit code 0
示例代码
m := map[string]int{"one":1,"two":2,"three":3} for k, v := range m { t.log(k, v) }
func testtracelmap(t *testing.t) { m1 := map[int]int{1: 1, 2: 4, 3: 9} for k, v := range m1 { t.log(k, v) } }
输出
=== run testtracelmap --- pass: testtracelmap (0.00s) map_test.go:34: 1 1 map_test.go:34: 2 4 map_test.go:34: 3 9 pass process finished with exit code 0
示例代码请访问:
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VSCode1.4 搭建Golang的开发调试环境(遇到很多问题)
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