less <运算符无法识别我是否设置了类似字符串PHP

I have strange problem with PHP. When I set the string like '<' and if I make new string with few strings then when is go to '<' is stop to working and go to next row of the script

$a = new SomeObject();
$a->where('id', 13332, "<");

public function where($column, $param, $operator = '=') {
    echo strlen($operator);
    if (isset($column) && strlen($operator) > 0) {
        echo $operator;
        if ($operator === '>') {
            $this->_where = ' WHERE ' . $column . '>?';
        } else if ($operator == '<') {
            $this->_where = ' WHERE ' . $column . '<?';
        } else if ($operator === '=') {
            $this->_where = ' WHERE ' . $column . '=?';
        } else {
            $this->_where = ' WHERE ' . $column . $operator . '?';
        }
        $this->_where = ' WHERE ' . $column . chr(0x3c) . '?';
        echo '<br/>' . $this->_where . '<br/>';
    } else {
        throw new \Exception('We need to have $column variable like string and $param like Param!', 500);
    }
    echo '<br/>c';
}

And the result is:

1< WHERE id c

And my question is why less < is cannot get like string. The > and = operators is OK. But the < just is not recognize. What I'm doing wrong?

Remove one line and it will work (test one below yourself):-

<?php
error_reporting(E_ALL); //check all type of errors
ini_set('display_errors',1); // display those if any happen

$a = new SomeObject();
$a->where('id', 13332, "<");

public function where($column, $param, $operator = '=') {
    echo strlen($operator);
    if (isset($column) && strlen($operator) > 0) {
        echo $operator;
        if ($operator === '>') {
            $this->_where = ' WHERE ' . $column . '> ?'; // added space
        } else if ($operator == '<') {
            $this->_where = ' WHERE ' . $column . '< ?'; // added space
        } else if ($operator === '=') {
            $this->_where = ' WHERE ' . $column . '= ?'; // added space
        } else {
            $this->_where = ' WHERE ' . $column . $operator . '?';
        }
        //$this->_where = ' WHERE ' . $column . chr(0x3c) . '?';  remove this line
        echo '<br/>' . $this->_where . '<br/>';
    } else {
        throw new \Exception('We need to have $column variable like string and $param like Param!', 500);
    }
    echo '<br/>c';
}

Note:-

Reason for not working:-

You have to add spaces too to make it correct(commented by @RiggsFolly) (For browser showing sake)

You are just over-writing your conditions. (commented and example by @JonStirling :- https://3v4l.org/vCO5Z) (for working purpose)

In this line:

$this->_where = ' WHERE ' . $column . chr(0x3e) . '?';

you overwrite your all previous changes so no wonder you can not see right result

Please try with this function and let me know will it gives you desired output

public function where($column, $param, $operator = '=') {
    echo strlen($operator);
    if (isset($column) && strlen($operator) > 0) {
        echo $operator;
        if ($operator === '>') {
            $this->_where = ' WHERE ' . $column . '> ?';
        } else if ($operator == '<') {
            $this->_where = ' WHERE ' . $column . '< ?';
        } else if ($operator === '=') {
            $this->_where = ' WHERE ' . $column . '= ?';
        } else {
            $this->_where = ' WHERE ' . $column . $operator . ' ?';
        }
        if($this->_where != '')
        {
            $this->_where .= ' and ' . $column . chr(0x3e) . ' ?';
        }
        else
        {
          $this->_where = ' WHERE ' . $column . chr(0x3e) . ' ?';
        }
        echo '<br/>' . $this->_where . '<br/>';
    } else {
        throw new \Exception('We need to have $column variable like string and $param like Param!', 500);
    }
    echo '<br/>c';
}