Discuss the implementation principles and usage of Golang atoi function

Golang is a programming language that has become increasingly popular in recent years. Its simplicity, efficiency, security and other features are favored by programmers. Golang has integrated many standard library functions internally, one of the more commonly used is the atoi function, which can convert a string into an integer. In this article, we will delve into the implementation principles and usage of the Golang atoi function.

1. The function of Golang atoi function

In Golang, the function of atoi function is to convert a string into an integer value. Its function prototype is: func Atoi(s string) (int, error). Among them, s is the string that needs to be converted, and the return value includes the converted integer value and an error. If the s string cannot be successfully converted to an integer value, an error is returned and 0 is returned as the default value.

2. The implementation principle of Golang atoi function

The implementation principle of Golang's atoi function is relatively simple. It mainly traverses the input string and converts the string into numerical value. During the traversal process, it also takes into account some basic error conditions, such as the string being empty, containing illegal characters, etc.

The following are the specific implementation steps of the Golang atoi function:

1. To remove whitespace symbols such as spaces or tabs at the beginning and end of a string, you can use the strings.Trim function.

2. Determine whether the string is a negative number. If it is a negative number, remove the sign and record it, and then add it back as needed.

3. Traverse each character in the string, obtain its corresponding value and accumulate it. If illegal characters are encountered during traversal, an error will be returned directly.

4. Determine whether the value exceeds the integer range. If so, an error will be returned and the maximum or minimum value will be returned as the default result.

The code is implemented as follows:

func Atoi(s string) (int, error) {

s = strings.Trim(s, " ")
if len(s) == 0 {
    return 0, errors.New("empty string")
}
sign := 1
if s[0] == '-' {
    sign = -1
    s = s[1:]
} else if s[0] == '+' {
    s = s[1:]
}
res := 0
for _, c := range []byte(s) {
    if c < &#39;0&#39; || c > '9' {
        return 0, errors.New("invalid character")
    }
    res = res*10 + int(c-'0')
    if res > math.MaxInt32 {
        return 0, errors.New("out of range")
    }
}
return sign * res, nil

}

3. How to use the Golang atoi function

The following is a sample code using the Golang atoi function for string conversion:

package main

import (

"fmt"
"strconv"

)

func main() {

str := "123"
num, err := strconv.Atoi(str)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println(num)

}

This example code first defines a string variable str, and then calls the strconv.Atoi function in the Golang standard library to convert the string into an integer type value and check if an error occurred. Finally, the converted integer value is printed to the console.

To sum up, the Golang atoi function is a very practical function that can help us quickly convert strings into integer values. Through the introduction of this article, we have understood the implementation principle and usage of the Golang atoi function, and I believe that readers can already use it skillfully.

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