bool，string

int，int8，int16，int32，int64，uintptr

byte，rune

float32，float64，complex64，complex128

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复数回顾

复数复习1

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强制类型转换

 var a, b int = 3, 4

var c int = math.Sqrt(a*a +  b*b)   ----> X

var c int = int(math.Sqrt(float64(a*a + b*b)))