Detailed explanation of how to use rand package in golang

Go is an open source programming language developed by Google. The characteristics of Go language are simplicity, speed, safety and concurrency. Go has a very popular standard library that includes many powerful and useful functions. One of them is the function in the rand package, which is used to generate pseudo-random numbers.

rand package provides some functions that can generate random numbers. These functions are pseudo-random number generators, which means they generate a sequence of numbers that looks random but is actually generated by a seed number. Using the same seed number will result in the same sequence of pseudo-random numbers. Therefore, when we need to ensure that the generated random numbers are unpredictable and meet higher security requirements, we need to use more complex random number generation algorithms.

The most commonly used functions in the rand package are Int, Intn and Float64. Their usage will be introduced below.

1. Int

The Int function returns a non-negative random integer in the range of [int64). The following is the usage of the Int function:

package main

import (
    "fmt"
    "math/rand"
)

func main() {
    // 产生一个随机整数
    var num int64 = rand.Int63()

    fmt.Println(num)
}

In the above code, we first import the "rand" and "fmt" packages, which are used to generate random numbers and output results on the console respectively. Then, we call the rand.Int63() function, which will return a 32-bit or 64-bit random integer. Note that the seed number used here is the system time, so the random numbers generated are different each time.

2. Intn

The Intn function returns a non-negative random integer in the range [0, n). The following is the usage of the Intn function:

package main

import (
    "fmt"
    "math/rand"
)

func main() {
    // 产生一个0-100的随机整数
    num := rand.Intn(100)

    fmt.Println(num)
}

In the above code, we call the rand.Intn(100) function, which will return an integer greater than or equal to 0 and less than 100.

3. Float64

The Float64 function returns a random floating point number in the range [0.0, 1.0). The following is the usage of the Float64 function:

package main

import (
    "fmt"
    "math/rand"
)

func main() {
    // 产生一个随机浮点数
    num := rand.Float64()

    fmt.Println(num)
}

In the above code, we call the rand.Float64() function, which will return a random floating point number greater than or equal to 0 and less than 1.

In addition to the above commonly used functions, the rand package also provides some other functions, such as:

• Int31: Returns a non-negative random integer in the range of [int32).
• Int63n: Returns a non-negative random integer in the range [0,n).
• Perm: Returns an integer sequence of [0,n) in random order.
• Shuffle: Shuffle a variable-length array in random order.

Summary: The rand package provides some simple and practical functions that can provide certain help in generating random numbers. But it should be noted that although the random numbers generated in the rand package look random, they are not actually truly random numbers. Therefore, when it is necessary to ensure that the generated random numbers are unpredictable and meet higher security requirements, a more complex random number generation algorithm needs to be used.

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