将 strpos() 与 >=0 或 == false 进行松散比较并不总是返回正确的结果

发布于 2024-07-25 14:16:15 字数 1187 浏览 12 评论 0原文

我只是想弄清楚这一点...

$mystring = "/abc/def/hij";
$find = "/abc";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) >= 0) {
    echo("found");
} else {
    echo("not found");
}

这将给出：

0
found

$mystring = "/abc/def/hij";
$find = "/fffff";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) >= 0) {
    echo("found");
} else {
    echo("not found");
}

输出：

[blank]
found

现在如果我更改比较器并使用 != False 而不是 >= 0：

$mystring = "/abc/def/hij";
$find = "/fffff";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) != false) {
    echo("found");
} else {
    echo("not found");
}

这几乎适用于所有情况，除了当我在字符串开头查找子字符串时。

这将输出“未找到”：

$mystring = "/abc/def/hij";
$find = "/abc";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) != false) {
    echo("found");
} else {
    echo("not found");
}

那么我怎样才能使其工作呢？我只想知道字符串中是否存在子字符串，如果子字符串是开头还是整个字符串，它应该给我 true 。

原文

I'm just trying to figure this out...

$mystring = "/abc/def/hij";
$find = "/abc";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) >= 0) {
    echo("found");
} else {
    echo("not found");
}

this will give :

0
found

$mystring = "/abc/def/hij";
$find = "/fffff";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) >= 0) {
    echo("found");
} else {
    echo("not found");
}

output:

[blank]
found

Now if I change the comparator and use != False instead of >= 0:

$mystring = "/abc/def/hij";
$find = "/fffff";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) != false) {
    echo("found");
} else {
    echo("not found");
}

This works in almost all cases, except when I look for the substring at the beginning of the string.

This will output "not found":

$mystring = "/abc/def/hij";
$find = "/abc";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) != false) {
    echo("found");
} else {
    echo("not found");
}

So how can I make that work? I just want to know if a substring exists in a string, and it should give me true if the substring is the beginning or the entire string.

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反话 2024-08-01 14:16:15

使用 !== 运算符进行测试。这将比较类型和值，而不是仅比较值：

$mystring = "/abc/def/hij";
$find = "/abc";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) !== false) {
    echo("found");
} else {
    echo("not found");
}

Test using the !== operator. This will compare types and values, as opposed to just values:

$mystring = "/abc/def/hij";
$find = "/abc";

echo(strpos($mystring, $find) . "<br>");
if (strpos($mystring, $find) !== false) {
    echo("found");
} else {
    echo("not found");
}

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