[PHP知识库]PHP Scanner

?要实现这种效果, 读取键盘输入

* index.php

<?php

include "Scanner.php";

class Solution {
    public static function main() {
        // $sc = new Scanner("php://stdin");
        $sc = new Scanner("./input/input.txt");
        while ($sc->hasNext()) {
            $rn = $sc->nextInt();
            printf("---- rn=%d ----\n", $rn);
            // fflush(STDOUT);
        }
    }
}

Solution::main();

命令行读取键盘输入， 文件路径填写 “php://stdin”

如果是http请求，文件路径填写 “php://input”

* Scanner.php

<?php

class Scanner {
    /** @var resource */
    protected $in;

    /**
     * Scanner constructor.
     * @param $uri "php://input", "file:///D:/Users/mingz/CLionProjects/nowcoder/huawei/core.txt"
     */
    public function __construct(/* string */$uri) {
        $this->in = fopen($uri, 'r');
    }

    private static function isBlank($c) {
        return strncmp($c, " ", 1) == 0 || strncmp($c, "\t", 1) == 0
            || strncmp($c, "\r", 1) == 0 || strncmp($c, "\n", 1) == 0;
    }

    /**
     * Get a word from resource $this->in, char by char
     * @return string
     */
    private function getWord() {
        $ch = fgetc($this->in);
        for (; !feof($this->in); $ch = fgetc($this->in)) {
            if (!self::isBlank($ch)) {break;}
        }
        // $at = ftell($this->in);
        $word = "";
        for (; !feof($this->in); ) {
            if (self::isBlank($ch)) {
                break;
            } else {
                $word .= $ch;
            }
            $ch = fgetc($this->in);
        }
        return $word;
    }

    private function _next() {
        return $this->getWord();
    }

    private static function atoi($s) {
        $num = 0;
        $i = 0;
        for (; isset($s[$i]); $i += 1) {
            if (!self::isBlank($s[$i])) {break;}
        }
        $codeMinus = ord("-");
        $negative = false;
        if (ord($s[$i]) == $codeMinus) {
            $negative = true;
            $i += 1;
        }
        $codeDot = ord(".");
        for (; isset($s[$i]); $i += 1) {
            $code = ord($s[$i]);
            if (48 <= $code && $code < 58) {
                $num = 10 * $num + ($code - 48);
            } elseif ($code == $codeDot) {
                break;
            }
            if ($num > PHP_INT_MAX) {
                throw new OutOfRangeException("Integer out of range: ".PHP_INT_MAX);
            }
        }
        if ($negative) {$num = 0 - $num;}
        return $num;
    }

    public function nextInt() {
        $nextWord = "";
        for (;;) {
            $nextWord = $this->_next();
            if (is_numeric($nextWord)) {break;}
        }
        return self::atoi($nextWord);
    }

    public function next() {return $this->_next();}
    public function hasNext() {
        return !feof($this->in);
    }
    public function __destruct() {fclose($this->in);}

    // -- for debug ---
    private static function bufDump(/* string */$buf) {
        if (!isset($buf[0])) {return "{}";}
        $n = strlen($buf);
        $s = "{". $buf[0];
        for ($i = 1; $i < $n; $i++) {
            $ch = $buf[$i];
            if ($ch == "\r") {$ch = "\\r";}
            else if ($ch == "\n") {$ch = "\\n";}
            $s .= "|". $ch;
        }
        return $s . "}";
    }
    private static function arrDump($a) {
        if (empty($a)) {return "[]";}
        $s = "[". $a[0];
        for ($i = 1; isset($a[$i]); $i += 1) {
            $s .= ",".$a[$i];
        }
        return $s."]";
    }
}

使用buffered reader很麻烦，一个字符一个字符读取算了