github.com/nibnait/go-learn@v0.0.0-20220227013611-dfa47ea6d2da/src/test/chapter/ch1/09_map_test.go (about)

     1  package ch1
     2  
     3  import "testing"
     4  
     5  func TestInitMap(t *testing.T) {
     6  	m1 := map[int]int{1: 1, 2: 4, 3: 9}
     7  	t.Log(m1[2])
     8  	t.Log("len m1", len(m1))
     9  
    10  	m2 := map[int]int{}
    11  	m2[4] = 16
    12  	t.Log("len m2", len(m2))
    13  
    14  	m3 := make(map[int]int, 10)
    15  	t.Log("len m3", len(m3))
    16  
    17  }
    18  
    19  func TestAccessNotExistingKey(t *testing.T) {
    20  	m1 := map[int]int{}
    21  	t.Log(m1[1])
    22  
    23  	m1[2] = 0
    24  	t.Log(m1[2])
    25  
    26  	m2 := map[int]string{}
    27  	t.Log(m2[1])
    28  
    29  	m2[2] = ""
    30  	t.Log(m2[2])
    31  
    32  	m1[3] = 3
    33  	if value, isExist := m1[3]; isExist {
    34  		t.Logf("key 3 存在。 value = %d", value)
    35  	} else {
    36  		t.Log("key 3 不存在")
    37  	}
    38  
    39  }
    40  
    41  func TestTravelMap(t *testing.T) {
    42  	m1 := map[int]int{1: 1, 2: 4, 3: 9}
    43  
    44  	for k, v := range m1 {
    45  		t.Log(k, v)
    46  	}
    47  }