Question

我正在尝试制作一个程序，该程序将询问用户一个数字，然后在数组中显示0到该数字之间的所有素数。

<?php

class SmallerPrimes{

public function __construct($file){

    $this->input_filename = $file;

}

public function Main(){

    $smaller_than = (int)$this->readString()[0];

    $result = array();        

     /* YOUR CODE HERE */          

     function isPrime($n) 
    { 
        if ($n <= 1) 

            return false; 

        for ($i = 2; $i < $n; $i++) 

            if ($n % $i == 0) 

                return false; 

        return true; 
    }         

    function printPrime($n) 
    { 
        for ($i = 2; $i <= $n; $i++)  
        { 
            if (isPrime($i)) 

                echo $i . " "; 
        } 
    }        
    $n = 7; 

    printPrime($n);              

     /*end of your code here */       

    return $result;
}

public function readString(){

    $file = fopen($this->input_filename, "r");

    $line = array();

    while (!feof($file)){

        array_push($line, str_replace(PHP_EOL, "", fgets($file)));
    }
    return $line;
}
}

$o = new SmallerPrimes($argv[1]);
echo implode(" ", $o->Main()) . PHP_EOL;

此代码有效，但固定了$ n。我不知道如何使用要求用户输入数字的输入这是一个验证自己并在可以的情况下向我们显示的代码

我要完成的代码就是这个（我们一开始只有这个）：

class SmallerPrimes{

public function __construct($file){

    $this->input_filename = $file;

}

public function Main(){

    $smaller_than = (int)$this->readString()[0];

    $result = array();

     /* YOUR CODE HERE */     

    return $result;

}

public function readString(){

    $file = fopen($this->input_filename, "r");

    $line = array();

    while (!feof($file)){

        array_push($line, str_replace(PHP_EOL, "", fgets($file)));

    }

    return $line;

    }
}

$o = new SmallerPrimes($argv[1]);

echo implode(" ", $o->Main()) . PHP_EOL;

Answer 1

这是您的脚本：

<?php
class SmallerPrimes{
public function __construct($file){
    $this->input_filename = $file;
}
public function Main(){
    $smaller_than = (int)$this->readString()[0];
    $result = array();
     function isPrime($n) {
        if ($n <= 1) return false;
        for ($i = 2; $i < $n; $i++) if ($n % $i == 0) return false;
        return true;
    }
    function printPrime($n) {
        for ($i = 2; $i < $n; $i++) if (isPrime($i)) $result[] = $i;
        return $result;
    }
    $result = printPrime($smaller_than);
    return $result;
}
public function readString(){
    $file = fopen($this->input_filename, "r");
    $line = array();
    while (!feof($file)){
        array_push($line, str_replace(PHP_EOL, "", fgets($file)));
    }
    return $line;
}}
$o = new SmallerPrimes($argv[1]);
echo implode(" ", $o->Main()) . PHP_EOL;

Answer 2

function getSmallerPrimes($smaller_than) {
    if ($smaller_than <= 2) {
        return [];
    }
    $result = [2];
    $sqrt = sqrt($smaller_than);

    for ($n = 3; $n < $smaller_than; $n += 2) {
        $isPrime = true;
        foreach($result as $prime) {
            if ($n % $prime == 0) {
                $isPrime = false;
                break;
            }
            if ($prime > $sqrt) {
                break;
            }
        }
        if ($isPrime) {
            $result[] = $n;
        }
    }
    return $result;
}

$input = 23;
echo implode(' ', getSmallerPrimes($input));

结果：2 3 5 7 11 13 17 19

从用户的输入php打印素数

2 个答案: