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go语言中有一些比较常用的内建函数，在这篇文章中将会进行简单的介绍。

内建函数

len & cap

map操作：delete

例子代码

[root@liumiaocn goprj]# cat basic-buildin1.gopackage mainimport "fmt"func main() {        m1 := make(map[string]int)        m1["Mon"] = 1        m1["Tue"] = 2        m1["Wed"] = 3        fmt.Println("before delete : m1=", m1, "len(m1)=", len(m1))        println("delete element by using key Tue")        delete(m1, "Tue")        fmt.Println("after  delete : m1=", m1, "len(m1)=", len(m1))}[root@liumiaocn goprj]#

执行结果

[root@liumiaocn goprj]# go run basic-buildin1.gobefore delete : m1= map[Mon:1 Tue:2 Wed:3] len(m1)= 3delete element by using key Tueafter  delete : m1= map[Mon:1 Wed:3] len(m1)= 2[root@liumiaocn goprj]#

slice操作

例子代码

[root@liumiaocn goprj]# cat basic-buildin2.gopackage mainimport "fmt"func main() {        a1 := new([10]int)        a1[4] = 5        a1[7] = 8        fmt.Println("a1= ", a1, "len(a1)=", len(a1), " cap(a1)=", cap(a1))        s1 := make([]int, 5, 10)        s1[0] = 5        s1[4] = 2        s2 := make([]int, 5, 10)        s2[0] = 1        s2[4] = 3        fmt.Println("before copy :s1= ", s1, "len(s1)=", len(s1), " cap(s1)=", cap(s1))        fmt.Println("before copy :s2= ", s2, "len(s2)=", len(s2), " cap(s2)=", cap(s2))        println("copy(s2,s1)")        copy(s2, s1)        fmt.Println("after  copy :s1= ", s1, "len(s1)=", len(s1), " cap(s1)=", cap(s1))        fmt.Println("after  copy :s2= ", s2, "len(s2)=", len(s2), " cap(s2)=", cap(s2))        println("reset")        s2[0] = 1        s2[4] = 3        fmt.Println("after  reset:s1= ", s1, "len(s1)=", len(s1), " cap(s1)=", cap(s1))        fmt.Println("after  reset :s2= ", s2, "len(s2)=", len(s2), " cap(s2)=", cap(s2))        println("append(s2,20)")        s2 = append(s2, 6)        fmt.Println("after  append:s1= ", s1, "len(s1)=", len(s1), " cap(s1)=", cap(s1))        fmt.Println("after  append:s2= ", s2, "len(s2)=", len(s2), " cap(s2)=", cap(s2))        s2 = append(s2, 7)        s2 = append(s2, 8)        s2 = append(s2, 9)        s2 = append(s2, 10)        fmt.Println("after  append:s2= ", s2, "len(s2)=", len(s2), " cap(s2)=", cap(s2))        s2 = append(s2, 11)        fmt.Println("after  append:s2= ", s2, "len(s2)=", len(s2), " cap(s2)=", cap(s2))}[root@liumiaocn goprj]#

执行结果

[root@liumiaocn goprj]# go run basic-buildin2.goa1=  &[0 0 0 0 5 0 0 8 0 0] len(a1)= 10  cap(a1)= 10before copy :s1=  [5 0 0 0 2] len(s1)= 5  cap(s1)= 10before copy :s2=  [1 0 0 0 3] len(s2)= 5  cap(s2)= 10copy(s2,s1)after  copy :s1=  [5 0 0 0 2] len(s1)= 5  cap(s1)= 10after  copy :s2=  [5 0 0 0 2] len(s2)= 5  cap(s2)= 10resetafter  reset:s1=  [5 0 0 0 2] len(s1)= 5  cap(s1)= 10after  reset :s2=  [1 0 0 0 3] len(s2)= 5  cap(s2)= 10append(s2,20)after  append:s1=  [5 0 0 0 2] len(s1)= 5  cap(s1)= 10after  append:s2=  [1 0 0 0 3 6] len(s2)= 6  cap(s2)= 10after  append:s2=  [1 0 0 0 3 6 7 8 9 10] len(s2)= 10  cap(s2)= 10after  append:s2=  [1 0 0 0 3 6 7 8 9 10 11] len(s2)= 11  cap(s2)= 20[root@liumiaocn goprj]#

复数操作

例子代码

[root@liumiaocn goprj]# cat basic-buildin3.gopackage mainimport "fmt"func main() {        var c1 = complex(1.1, 2)        var r1 = real(c1)        var i1 = imag(c1)        println("c1=", c1, " r1=", r1, " i1=", i1)        fmt.Println("c1=", c1, " r1=", r1, " i1=", i1)}[root@liumiaocn goprj]#

执行结果

[root@liumiaocn goprj]# go run basic-buildin3.goc1= (+1.100000e+000+2.000000e+000i)  r1= +1.100000e+000  i1= +2.000000e+000c1= (1.1+2i)  r1= 1.1  i1= 2[root@liumiaocn goprj]#

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