使用CAtlRegExp正则表达式检查浮点数输入

一、VS2008(Sp1)环境使用CAtlRegExp类需要额外下载ATL Server，（因为开源代码，没集成在VS2008里了） http://atlserver.codeplex.com/

二、下载后解压，如F:\CPP\ATL_Server_Source_and_Headers_9_0_70425_Alpha

然后设置路径：【工具】->【选项】->【项目和解决方案】->【VC++目录】，在【包含文件】添加目录 F:\CPP\ATL_Server_Source_and_Headers_9_0_70425_Alpha\include

三、使用方法

    (1)、h文件中

包含头文件  

     #include <atlrx.h>

变量

CString m_szPixels;

float m_nPixels;

定义函数

static CString REError2String(REParseError status);

    (2)、CPP实现文件

主要代码添加在DoDataExchange();

void CPageMeasument::DoDataExchange(CDataExchange* pDX)
 
 
 

   {
 
 
 

      CPropertyPage::DoDataExchange(pDX);
 
 
 

      DDX_Text(pDX, IDC_EDIT1, m_szPixels);
 
 
 

      DDX_Text(pDX, IDC_EDIT2, m_nDefaultZoomFactor);
 
 
 

      DDX_Control(pDX, IDC_COMBO_UNITS, m_cboUnits);
 
 
  
 

 
 
    
     CString szErr(_T("Parser Error:"));
 
 
 
 
 
 

 
 
    if ( pDX->m_bSaveAndValidate ) {
 
 
    // create regular expression content
 
 
    CAtlRegExp<> regex;
 
 
    REParseError status = regex.Parse(L"^{[-+]?\\d+}{\\.}?{\\d*}{[eE][-+]?\\d+}?$");   
 
 
    if (REPARSE_ERROR_OK != status) {
 
 
    // invalid pattern, show error
 
 
    
 
 
    } else {
 
 
    // valid regex pattern, now try to match the content
 
 
    CAtlREMatchContext<> mc;
 
 
    if (!regex.Match(m_szPixels, &mc)) {
 
 
        // content not match
 
 
        m_szPixels = _T("");
 
 
        m_nPixels = -1;
 
 
    } else {
 
 
        // content match, show match-group like this
 
 
        // for (UINT nGroupIndex = 0; nGroupIndex < mc.m_uNumGroups; ++nGroupIndex)
 
 
        // {
 
 
        // const CAtlREMatchContext<>::RECHAR* szStart = 0;
 
 
    // const CAtlREMatchContext<>::RECHAR* szEnd = 0;
 
 
    // mc.GetMatch(nGroupIndex, &szStart, &szEnd);
 
 
    // ptrdiff_t nLength = szEnd - szStart;
 
 
    // CString text(szStart, nLength);
 
 
    //                                       //text是各个拆开后的字符串，可以打印出来
 
 
    // }
 
 

 
 
    m_nPixels  = (float)_tstof((const wchar_t*)m_szPixels.GetBuffer(0));
 
 
    }
 
 
    }
 
 
               //print error message "szErr" here
 
 
              //AfxMessageBox(szErr);  
 
 
    }
 
 

   }
 
 

 

  定义错误函数

 
 
 

   CString CPageMeasument::REError2String(REParseError status)
 
 
 

   {
 
 
 

      switch (status) {
 
 
 

      case REPARSE_ERROR_OK: return TEXT("No error occurred");
 
 
 

      case REPARSE_ERROR_OUTOFMEMORY: return TEXT("Out of memory");
 
 
 

      case REPARSE_ERROR_BRACE_EXPECTED: return TEXT("A closing brace was expected");
 
 
 

      case REPARSE_ERROR_PAREN_EXPECTED: return TEXT("A closing parenthesis was expected");
 
 
 

      case REPARSE_ERROR_BRACKET_EXPECTED: return TEXT("A closing bracket was expected");
 
 
 

      case REPARSE_ERROR_UNEXPECTED: return TEXT("An unspecified fatal error occurred");
 
 
 

      case REPARSE_ERROR_EMPTY_RANGE: return TEXT("A range expression was empty");
 
 
 

      case REPARSE_ERROR_INVALID_GROUP: return TEXT("A back reference was made to a group that did not exist");
 
 
 

      case REPARSE_ERROR_INVALID_RANGE: return TEXT("An invalid range was specified");
 
 
 

      case REPARSE_ERROR_EMPTY_REPEATOP: return TEXT("A repeat operator (* or +) was applied to an expression that could
     be empty");
 
 
 

      case REPARSE_ERROR_INVALID_INPUT: return TEXT("The input string was invalid");
 
 
 

      default: return TEXT("Unknown error");
 
 
 
}
 
 
 

   }
 
 
 
 
  
 
 
 
  
 

    {
  
 
  
 
   
 
  
UpdateData(TRUE);
  
 
  
 
   
 
  
if ((m_nPixels <= 0) && (BST_CHECKED==((CButton*)GetDlgItem(IDC_CHECK1))->GetCheck()))
  
 
  
{
  
 
  

       CRect rect;
  
 
  

       GetDlgItem(IDC_EDIT1)->GetWindowRect(&rect);
  
 
  

       CPoint pt = rect.CenterPoint(); pt.x = rect.right-15;
  
 
  

       m_tooltip.SetDirection(PPTOOLTIP_LEFTEDGE_TOP);
  
 
  

       m_tooltip.ShowHelpTooltip(&pt, _T("<center><h2>Check input</h2><br><hr color=blue></center><br>You maybe enter a illegal values"));
  
 
  

       return ;
  
 
  
}
  
 
  
 
   
 
  
if ((m_cboUnits.GetCurSel() <  0)  && (BST_CHECKED==((CButton*)GetDlgItem(IDC_CHECK1))->GetCheck()) )
  
 
  
{
  
 
  
CRect rect;
  
 
  
GetDlgItem(IDC_COMBO_UNITS)->GetWindowRect(&rect);
  
 
  
CPoint pt = rect.CenterPoint(); pt.x = rect.right-15;
  
 
  
m_tooltip.SetDirection(PPTOOLTIP_LEFTEDGE_TOP);
  
 
  
m_tooltip.ShowHelpTooltip(&pt, _T("<center><h2>Check input</h2><br><hr color=blue></center><br>Select a units"));
  
 
  
return ;
  
 
  
}
  
 
  
 
   
 
  
CPropertyPage::OnOK();
  
 
  

    }

四、说明

^{[-+]?\\d+}{\\.}?{\\d*}{[eE][-+]?\\d+}?$ ，本来语法是   ^([-+]?\d+)(\.)?(\d*)([eE][-+]?\d+)?$

()改成 {}才行，列外C++代码里面 \要用转义字符  \\ 表示，所以 \d 写成 \\d

^{[-+]?\\d+}{\\.}?{\\d*}{[eE][-+]?\\d+}?$"   表示是Unicode字符串，前面加个L 修饰

这个正则表达式表示的浮点数可以是：

-.2   -0.2   +0  +0.   +.2   1.23    -1.23   +1.23e-3    +1.23E+3  -1.23e-5   123  123.     123.e-3

等等各种合法浮点数。。

列外在这个网站​​http://regexlib.com/​​ 可以搜到很多现成的一些正则表达式。。。。。。。。。

五、结果，检测非法输入