我使用以下代碼得到以下錯(cuò)誤：

注意：未定義的變量：第35行的C：\ xampp \ htdocs \ test \ projects \ Learning \ php \ Databases \ Forms和Databases \ project.php中的錯(cuò)誤

代碼：

$clicked = false;

if($clicked == false && isset($_POST['submit'])) {

if ($_POST['label'] == '') {

echo "

You must enter in a label!

";

$error = true;

}

if ($_POST['url'] == '') {

echo "

You must enter in a url!

";

$error = true;

}

if ($_POST['status'] == '') {

echo "

You must enter in a status (0 or 1)!

";

$error = true;

}

}

if ($error != true) {

if (isset($_POST['submit']) && $_POST['submit'] == '1' ) {

$query = "INSERT INTO nav (label, url, target, status, position) VALUES ('$_POST[label]', '$_POST[url]', '$_POST[target]', $_POST[status], $_POST[position])";

$result = mysqli_query($dbc, $query);

if ($result) {

echo "

You've added a new navigation link!

";

}

else {

echo "

An error has occured!

";

echo mysqli_error($dbc);

echo '

'.$query.'

';

}

$clicked = true;//submit button replaced

}

}

?>

Navigation

*Required Fields

*Label:

Position:

*URL:

Target:

*Status:

if ($clicked == false) {

echo '

Add Navigation Link

';

}

else {

echo '

Do Another

';

}

?>

當(dāng)我做出以下更改時(shí)：

if($clicked == false && $_POST['submit'] == "1") {

if ($_POST['label'] == '') {

echo "

You must enter in a label!

";

$error = true;

}

if ($_POST['url'] == '') {

echo "

You must enter in a url!

";

$error = true;

}

if ($_POST['status'] == '') {

echo "

You must enter in a status (0 or 1)!

";

$error = true;

}

}

我收到這些錯(cuò)誤：

注意：未定義的索引：在第18行的C：\ xampp \ htdocs \ test \ projects \ Learning \ php \ Databases \ Forms和Databases \ project.php中提交

＆

注意：未定義的變量：第35行的C：\ xampp \ htdocs \ test \ projects \ Learning \ php \ Databases \ Forms和Databases \ project.php中的錯(cuò)誤

很明顯，名稱(chēng)“提交”的按鈕不會(huì)因任何原因被“看到”;我相信 . 這對(duì)我來(lái)說(shuō)有點(diǎn)意義，有點(diǎn)......如果我沒(méi)有弄錯(cuò)：php從頭到尾以線性方式讀取，并且因?yàn)楸韱卧趇f語(yǔ)句之下，所以索引還不存在 . 我認(rèn)為這進(jìn)一步證實(shí)了這樣一個(gè)事實(shí)：一旦我單擊提交按鈕，所有錯(cuò)誤都會(huì)消失，因此執(zhí)行if語(yǔ)句中的if語(yǔ)句的錯(cuò)誤(echo)語(yǔ)句 .

這令人難以置信 . 這也不起作用......

if(isset($_POST['submit']) && $_POST['submit'] == '1') {

if (isset($_POST['label']) && $_POST['label'] == '') {

echo "

You must enter in a label!

";

$error = true;

}

if (isset($_POST['url']) && $_POST['url'] == '') {

echo "

You must enter in a url!

";

$error = true;

}

if (isset($_POST['status']) && $_POST['status'] == '') {

echo "

You must enter in a status (0 or 1)!

";

$error = true;

}

}

...在以前版本的代碼中，isset和"is equal to"的組合用于if語(yǔ)句's conditions, solved the Unidentified index problem, as it pertained to the $_POST[' submit '], here' s代碼：ps：因?yàn)樗鼘儆谶@個(gè)特定的代碼塊，以下鏈接的伙伴tutorial盡管我和他做了完全相同的事情，但我正在跟隨它，并沒(méi)有出現(xiàn)任何這些錯(cuò)誤 .

$clicked = false;

if (isset($_POST['submit']) && $_POST['submit'] == '1' ) {

$query = "INSERT INTO nav (label, url, target, status, position) VALUES ('$_POST[label]', '$_POST[url]', '$_POST[target]', $_POST[status], $_POST[position])";

$result = mysqli_query($dbc, $query);

if ($result) {

echo "

You've added a new navigation link!

";}

else {

echo "

An error has occured!

";

echo mysqli_error($dbc);

echo '

'.$query.'

';

}

$clicked = true;//submit button replaced

}

?>

Navigation

*Required Fields

*Label:

Position:

*URL:

Target:

*Status:

if ($clicked == false) {

echo '

Add Navigation Link

';

}

else {

echo '

Do Another

';

}

?>

再次，這工作得很好，沒(méi)有錯(cuò)誤 . 那么為什么我在我發(fā)布的第一個(gè)代碼塊中得到了undefine變量錯(cuò)誤？未定義的變量是由于后續(xù)的if語(yǔ)句未能執(zhí)行而導(dǎo)致的，這就是我假設(shè)與索引問(wèn)題有關(guān)的問(wèn)題，但是，錯(cuò)誤并沒(méi)有反映出來(lái)！

當(dāng)我用$ clicked == false替換條件時(shí)，如下所示：

$clicked = false;

if($clicked == false) {

if ($_POST['label'] == '') {

echo "

You must enter in a label!

";

$error = true;

}

if ($_POST['url'] == '') {

echo "

You must enter in a url!

";

$error = true;

}

if ($_POST['status'] == '') {

echo "

You must enter in a status (0 or 1)!

";

$error = true;

}

}

我得到了這三個(gè)未定義的索引錯(cuò)誤ALONG WITH BLOODY CODE，它顯然成功執(zhí)行，盡管三個(gè)索引被認(rèn)為是未定義的：

注意：未定義的索引：第20行的C：\ xampp \ htdocs \ test \ projects \ Learning \ php \ Databases \ Forms和Databases \ project4.php中的標(biāo)簽?zāi)仨気斎霕?biāo)簽！

注意：未定義的索引：第24行的C：\ xampp \ htdocs \ test \ projects \ Learning \ php \ Databases \ Forms和Databases \ project4.php中的url你必須輸入一個(gè)url！

注意：未定義的索引：第28行的C：\ xampp \ htdocs \ test \ projects \ Learning \ php \ Databases \ Forms和Databases \ project4.php中的狀態(tài)您必須輸入狀態(tài)(0或1)！

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