检测负数

Question

我想知道是否还有检测PHP中的数字是否为负数？

我有以下代码

$profitloss = $result->date_sold_price - $result->date_bought_price;

我需要找出$ profitloss是否是负面的...如果是我需要回应它是的.

Answer 1

我相信这就是你要找的东西:

class Expression {
    protected $expression;
    protected $result;

    public function __construct($expression) {
        $this->expression = $expression;
    }

    public function evaluate() {
        $this->result = eval("return ".$this->expression.";");
        return $this;
    }

    public function getResult() {
        return $this->result;
    }
}

class NegativeFinder {
    protected $expressionObj;

    public function __construct(Expression $expressionObj) {
        $this->expressionObj = $expressionObj;
    }

    public function isItNegative() {
        $result = $this->expressionObj->evaluate()->getResult();

        if($this->hasMinusSign($result)) {
            return true;
        } else {
            return false;
        }
    }

    protected function hasMinusSign($value) {
        return (substr(strval($value), 0, 1) == "-");
    }
}

用法:

$soldPrice = 1;
$boughtPrice = 2;
$negativeFinderObj = new NegativeFinder(new Expression("$soldPrice - $boughtPrice"));

echo ($negativeFinderObj->isItNegative()) ? "It is negative!" : "It is not negative :(";

但请注意,eval是一个危险的函数,因此只有当你确实需要找出一个数字是负数时才使用它.

:-)

Answer 2

if ($profitloss < 0)
{
   echo "The profitloss is negative";
}

编辑:我觉得这对于代表来说太简单了,所以这里有一些你可能会觉得有帮助的东西.

在PHP中,我们可以通过使用abs()函数找到整数的绝对值.例如,如果我试图解决两个数字之间的差异,我可以这样做:

$turnover = 10000;
$overheads = 12500;

$difference = abs($turnover-$overheads);

echo "The Difference is ".$difference;

这会产生The Difference is 2500.

Answer 3

if(x < 0)
if(abs(x) != x)
if(substr(strval(x), 0, 1) == "-")

Answer 4

你可以检查一下 $profitloss < 0

if ($profitloss < 0):
    echo "Less than 0\n";
endif;

Answer 5

if ( $profitloss < 0 ) {
   echo "negative";
};

Answer 6

不要误会我的意思，但你可以这样做;)

function nagitive_check($value){
if (isset($value)){
    if (substr(strval($value), 0, 1) == "-"){
    return 'It is negative<br>';
} else {
    return 'It is not negative!<br>';
}
    }
}

输出：

echo nagitive_check(-100);  // It is negative
echo nagitive_check(200);  // It is not negative!
echo nagitive_check(200-300);  // It is negative
echo nagitive_check(200-300+1000);  // It is not negative!