GO Language Study Notes 2-int type ranges

int type, compared to C / C ++ language, GO language offers a variety of type int to choose from, there is int8, int16, int32, int64, int, uint8, uint16, uint32, uint64, uint.

1.int range type

• int8: -128 ~ 127
• int16: -32 768 ~ 32767
• int32: -2147483648 ~ 2147483647
• int64: -9223372036854775808 ~ 9223372036854775807
• uint8: 0 ~ 255
• uint16: 0 ~ 65535
• uint32: 0 ~ 4294967295
• uint64: 0 ~ 18446744073709551615

2. With regard to type int

• GO language type int size is uncertain, it has a relationship with a specific platform
• Generally, int is 4 bytes in the 32-bit system, is 8 bytes in the 64-bit system
• Deriving automatically initialized using a type integer, the default is int type

3. Example

package main

import (
    "fmt"
    "math"
    "unsafe"
)

func main() {
    // 输出各int类型的取值范围
    fmt.Println("各int类型的取值范围为：")
    fmt.Println("int8:", math.MinInt8, "~", math.MaxInt8)
    fmt.Println("int16:", math.MinInt16, "~", math.MaxInt16)
    fmt.Println("int32:", math.MinInt32, "~", math.MaxInt32)
    fmt.Println("int64:", math.MinInt64, "~", math.MaxInt64)
    fmt.Println()
    
    // n是自动推导类型
    n := 1234567890
    fmt.Printf("n := 1234567890 的默认类型为：%T\n", n)
    fmt.Printf("int类型的字节数为：")
    fmt.Println(unsafe.Sizeof(n))
    fmt.Printf("\n")

    // 初始化一个32位整型值
    var a int32 = 987654321

    fmt.Println("var a int32 = 987654321")
    // 输出变量的十六进制形式和十进制值
    fmt.Printf("int32: 十六进制为0x%x，十进制为%d\n", a, a)

    // 将a转换为int8类型, 发生数值截断
    b := int8(a)
    // 输出变量的十六进制形式和十进制值
    fmt.Printf("int8: 十六进制为0x%x，十进制为%d\n", b, b)

    // 将a转换为int16类型, 发生数值截断
    c := int16(a)
    // 输出变量的十六进制形式和十进制值
    fmt.Printf("int16: 十六进制为0x%x，十进制为%d\n", c, c)

    // 将a转换为int64类型
    d := int64(a)
    // 输出变量的十六进制形式和十进制值
    fmt.Printf("int64: 十六进制为0x%x，十进制为%d\n", d, d)

Code output:

各int类型的取值范围为：
int8: -128 ~ 127
int16: -32768 ~ 32767
int32: -2147483648 ~ 2147483647
int64: -9223372036854775808 ~ 9223372036854775807

n := 1234567890 的默认类型为：int
int类型的字节数为：8

var a int32 = 987654321
int32: 十六进制为0x3ade68b1，十进制为987654321
int8: 十六进制为0x-4f，十进制为-79
int16: 十六进制为0x68b1，十进制为26801
int64: 十六进制为0x3ade68b1，十进制为987654321

4. Summary

Due to the different languages ​​GO range of each type int, int types among the data conversion, data truncation will present problems in the course to attract attention.

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