c++ 上传文件到服务器代码

上传文件到服务器的代码可以使用以下步骤：

1. 在 HTML 中创建一个表单，包含一个文件上传字段：

<form action="upload.php" method="post" enctype="multipart/form-data">
  Select file to upload:
  <input type="file" name="fileToUpload" id="fileToUpload">
  <input type="submit" value="Upload File" name="submit">
</form>

2. 在服务器端创建一个 PHP 文件（例如 upload.php），用于处理上传文件的请求。

3. 在 PHP 文件中，可以使用 $_FILES 变量来获取上传的文件信息。例如，可以使用以下代码来获取上传的文件名和临时文件路径：

$target_dir = "uploads/";  // 上传文件的目标文件夹
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$temp_file = $_FILES["fileToUpload"]["tmp_name"];

4. 然后，可以使用 move_uploaded_file() 函数将文件从临时文件夹移动到目标文件夹：

if (move_uploaded_file($temp_file, $target_file)) {
  echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
} else {
  echo "Sorry, there was an error uploading your file.";
}

完整的上传文件到服务器的 PHP 代码如下所示：

<?php
$target_dir = "uploads/";  // 上传文件的目标文件夹
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$temp_file = $_FILES["fileToUpload"]["tmp_name"];
$uploadOk = 1;

// 检查文件是否已经存在
if (file_exists($target_file)) {
  echo "Sorry, file already exists.";
  $uploadOk = 0;
}

// 检查文件大小是否合法
if ($_FILES["fileToUpload"]["size"] > 500000) {
  echo "Sorry, your file is too large.";
  $uploadOk = 0;
}

// 允许上传的文件类型
$allowed_types = array("jpg", "jpeg", "png", "gif");
$file_type = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));
if (!in_array($file_type, $allowed_types)) {
  echo "Sorry, only JPG, JPEG, PNG, GIF files are allowed.";
  $uploadOk = 0;
}

// 检查上传是否成功
if ($uploadOk == 0) {
  echo "Sorry, your file was not uploaded.";
} else {
  if (move_uploaded_file($temp_file, $target_file)) {
    echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
  } else {
    echo "Sorry, there was an error uploading your file.";
  }
}
?>