Convert IP address to integer

Question part

topic	Convert IP address to integer
difficulty	easy
Question description	There is a virtual IPv4 address, which consists of 4 sections. Each section ranges from 0 to 255, separated by #. The virtual IPv4 address can be converted to a 32-bit integer, for example: 128#0#255#255, converted to The result of the 32-bit integer is 2147549183 (0x8000FFFF) 1#0#0#0. The result of conversion to a 32-bit integer is 16777216 (0x01000000). Now a virtual IPv4 address is given in the form of a string, limiting the range of section 1 to 1 ~ 128, that is, the range of each section is (1~128)#(0~255)#(0~255)#(0~255). It is required that each IPv4 address can only correspond to a unique integer. If it is an illegal IPv4, invalid IP is returned.
Enter description	Enter one line, virtual IPv4 address format string.
Output description	Output the IPv4 corresponding integer, or "invalid IP" as required.
Additional information	When entering an IPv4 address that may be illegal, you need to identify illegal IPv4 (empty strings, characters that do not exist in the IP address, illegal #, decimal integers not within the legal range, etc.).
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Example
Example 1
enter	100#101#1#5
output	1684340997
illustrate	none
Example 2
enter	1#2#3
output	invalid IP
illustrate

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Interpretation and analysis

Item explanation：

Input a string and convert it into the corresponding integer; if there is an illegal input, output "invalid IP".

Analysis Yoshiro：

The idea of ​​​​this question is relatively simple:
1. Determine whether it is an illegal input.
2. If it is illegal, output invalid IP. If it is legal, use "#" as the delimiter and divide it into 4 integers. The first integer * 256 * 256 * 256, plus the second integer * 256 * 256, plus the third integer * 256, plus The 4th integer. Output the final result.

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Code

Java code

import java.util.Scanner;

/**
 * IPv4转换成整数
 * 
 * @since 2023.11.20
 * @version 0.1
 * @author Frank
 *
 */
public class IPv4Convert2Int {

    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	while (sc.hasNext()) {
	    String input = sc.nextLine();
	    processIPv4Convert2Int(input);
	}

    }

    private static void processIPv4Convert2Int(String input) {
	String invalidIP = "invalid IP";
	if( input == null || input.length() == 0 )
	{
	    System.out.println(invalidIP);
	    return;
	}
	String[] ipSegments = input.split( "#" );
	if( ipSegments.length != 4 )
	{
	    System.out.println(invalidIP);
	    return;
	}
	
	int result = 0;
	for( int i = 0; i < ipSegments.length; i ++ )
	{
	    int tmpNum;
	    try {
		tmpNum = Integer.parseInt( ipSegments[i] );
	    }catch( NumberFormatException e)
	    {
		 System.out.println(invalidIP);
		 return;
	    }
	    if( i == 0 && ( tmpNum < 1 || tmpNum > 128 ))
	    {
		 System.out.println(invalidIP);
		 return;
	    }
	    if( i >= 1 && ( tmpNum < 0 || tmpNum > 255 ))
	    {
		 System.out.println(invalidIP);
		 return;
	    }
	    result = result * 256 + tmpNum;
	}
	System.out.println( result );
    }

}

JavaScript code

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;
void async function() {
    while (line = await readline()) {
        processIPv4Convert2Int(line);
    }
}();

function processIPv4Convert2Int( line ) {
    var invalidIP = "invalid IP";
    if( line == null || line.length == 0)
    {
        console.log( invalidIP );
        return;
    }
    var ipSegments = line.split("#");
    if( ipSegments.length != 4 )
    {
        console.log( invalidIP );
        return;
    }
    var result = 0;
    for( var i = 0; i < ipSegments.length; i ++ )
    {
        var tmpNum = parseInt( ipSegments[i] );
        if( isNaN( tmpNum ))
        {
            console.log( invalidIP );
            return;
        }
        if( i == 0 && ( tmpNum < 1 || tmpNum > 128 ))
        {
            console.log( invalidIP );
            return;
        }
        if( i >= 1 && ( tmpNum < 0 || tmpNum > 255 ))
        {
            console.log( invalidIP );
            return;
        }
        result = result * 256 + tmpNum;
    }
    console.log( result );
}

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