Question

是否有更好的方法在c / c ++中创建环境变量的路径？

<script>
    function readrecord() {
    document.main.action = "Login.php";
    document.getElementById("op").value = "check";
    document.main.submit(); 
}

function Userdontexist() {
  alert("Username or Password is wrong");
}

function submitForm() {
    Traveler_Username = document.getElementById('Traveler_Username').value;
    Password = document.getElementById('Password').value;

        if (Traveler_Username == "" || Password == "") {
            alert("Need to fill al the fields");
            return;
      } else {
        readrecord();
}}
</script>

<?php
include 'DB_connection.php';
    if (isset($_REQUEST["op"])) $op = $_REQUEST["op"]; else  $op = "";
    if (isset($_REQUEST["Traveler_Username"])) $Traveler_Username = $_REQUEST["Traveler_Username"]; 
    if (isset($_REQUEST["Password"])) $Password = $_REQUEST["Password"];

if ($op=="check") {
    $query = "select * from users where Traveler_Username =".$Traveler_Username;
        $result = mysql_query($query) or die('Query failed: ' . mysql_error());
        if (mysql_num_rows($result) == 0 ){
            alert("User do not exist");
            $Traveler_Username  = "";
            $Password   = "";
            header("Location: reg.php");
            exit;
        } else {
                $query = "select Password from users where Traveler_Username =".$Traveler_Username;
                $result = mysql_query($query) or die('Query failed: ' . mysql_error());
                $row = mysql_fetch_array($result);
                $db_pass = $row["Password"];
                if ($Password == $db_pass){
                    $Traveler_Username = $row['Traveler_Username'] ;
                    $Password = $row['Password'] ;
                    } else {
                            echo '<script> Userdontexist(); </script>';
                    }
            } // end else
} // end if

?>
                <tr>
                <td style="width: 95px;">Username</td>
                <td dir="rtl" style=" text-align: center; width: 195px;">
                <form method="post" target="_blank">
                <input id="Traveler_Username" type="text" dir="rtl" size="10" />
                    </form>
                </td>
                <td>&nbsp;</td>
            </tr>

            <tr>
                <td></td>
                <td class="he_shadow" style="text-align: center; width: 70px;">&nbsp;</td>
                <td style="width: 95px;">Password</td>
                <td dir="rtl" style=" text-align: center; width: 195px;">
                <form method="post" target="_blank">                
                    <input id="Password" name="Password" type="password" dir="rtl" size="10" />
                    </form>
                </td>
                <td></td>
            </tr>

            <tr>
                <td rowspan="2">&nbsp;</td>
                <td style="text-align: center; width: 70px;" rowspan="2">
                &nbsp;</td>
                <td style="width: 95px" rowspan="2">
                <form method="post" target="_blank">
                <input name="Submit1" type="submit" value="login"  onclick="readrecord()" style="width: 43px" />
                </form></td>
                <td style="text-align: center; border-bottom-color: #FF9900; width: 195px; height: 30px;">
                <input name="Reset1" type="reset" value="clear data" /></td>
                <td rowspan="2">&nbsp;</td>
            </tr>
            <tr>
                <td style="text-align: center; border-bottom-color: #FF9900; width: 195px;">
                &nbsp;</td>
            </tr>
            <tr>
                <td>&nbsp;</td>
                <td style="text-align: center; width: 70px;">
                &nbsp;</td>
                <td style="width: 95px">
                &nbsp;</td>
                <td style="text-align: center; border-bottom-color: #FF9900; width: 195px;">
                &nbsp;</td>
                <td>&nbsp;</td>
            </tr>

</div>

Answer 1

我建议让用户个人资料目录像这样。

BOOL GetCurrentUserDir(LPTSTR lpszBuf, LPDWORD lpdwBuflen)
{
    HANDLE hProcessToken;

    if (!OpenProcessToken(GetCurrentProcess(), TOKEN_READ, &hProcessToken))
        return FALSE;

    if (!GetUserProfileDirectory(hProcessToken, lpszBuf, lpdwBuflen)) {
        CloseHandle(hProcessToken);
        return FALSE;
    }

    CloseHandle(hProcessToken);
    return TRUE;
}

我像这样使用这个功能：

WCHAR szLocalPath[MAX_PATH];
if (!GetCurrentUserDir(szLocalPath, &cchPath))
{
    //Handle the error
}

然后您可以追加路径的其余部分。

这封装了特定的环境变量并使用了Win32 API。随着时间的推移，这更有可能保持便携性。

Answer 2

为什么不使用std :: string？

std::string s1 = std::getenv("SystemDrive");
s1 += "\\\\Users\\\\" + std::getenv("USERNAME") + "\\\\Documents";

Answer 3

连接多个字符串的一个好方法是使用snprintf：

char buf[0x10000];
int n = std::snprintf(buf, sizeof buf, "%s\\\\Users\\\\%s\\\\Documents", S1, S2);
if(static_cast<size_t>(n) >= sizeof buf)
    // Buffer is too small (if n > 0) or error

snprintf不会溢出缓冲区并始终为零终止的事实会使不安全的函数strcpy，strncpy，strcat变得不必要。

Answer 4

不确定完全了解您的需求。这是从环境变量创建路径吗？或者获取系统目录的正确路径？在后一种情况下，您最好使用Win32 API，例如：SHGetFolderPath或SHGetKnownFolderPath。

#include <Windows.h>
#include <ShellAPI.h>
#include <KnownFolders.h>
#include <ShlObj.h>

int main()
{
    CoInitialize(NULL);
    TCHAR* path = 0;
    SHGetKnownFolderPath(FOLDERID_Documents, KF_FLAG_SIMPLE_IDLIST, NULL, &path);
    // use collected 'path' here
    CoTaskMemFree(path);    // free the TCHAR object allocated by SHGetKnownFolderPath
    return 0;
}

以上代码检索当前用户＆＃34;我的文档＆＃34;文件夹路径。

Answer 5

std::getenv已被弃用。

我会用喜欢的东西：

char*  wSystemDrive = nullptr;
size_t wSize = 0;

bool wFree = true;

if(_dupenv_s(&wSystemDrive,&wSize,"SystemDrive") != 0 || wSystemDrive == nullptr)
{
    wFree = false;

    wSystemDrive = "C:\\"; //or anything default you want to use
}

std::string wSysteDriveString(wSystemDrive);

if(wFree)
{
    free(wSystemDrive);
}

char*  wUSERNAME = nullptr;
wSize = 0;

wFree = true;

if(_dupenv_s(&wEnv,&wSize,"wUSERNAME") != 0 || wUSERNAME == nullptr)
{
    wFree = false;

    wUSERNAME = "User";
}

std::string wUSERNAMEString(wUSERNAME);

if(wFree)
{
    free(wUSERNAME);
}

std::string wPath = wSystemDriveString + "\\Users\\" + wUSERNAMEString + "\\Documents"

请注意，您不需要4 \（\\\\），只需要两个\\。

是否有更好的方法在c / c ++中创建环境变量的路径？

5 个答案: