和字符串CString类相关的一些常用的函数

1.GetFileExt  该函数返回一个文件的扩展名，例如lihui.ext，会返回“txt”，常用在文件对话框中，对某个文件的扩展名的判断上

CFileDialog::GetFileExt

CString GetFileExt( ) const;

Return Value

The extension of the filename.

Remarks

Call this function to retrieve the extension of the filename entered into the dialog box. For example, if the name of the file entered is DATA.TXT, GetFileExt returns "TXT".

2. MakeLower   该函数可以把大写字母变成小写字母

CString::MakeLower

void MakeLower( );

Remarks

Converts this CString object to a lowercase string.

// example for CString::MakeLower
CString s( "ABC" );
s.MakeLower();
ASSERT( s == "abc" );

3.  Compare  用来比较两个字符串是否相同，如果相同的话，就返回0，不同的话再做比较  

CString::Compare

int Compare( LPCTSTR lpsz ) const;

Return Value

Zero if the strings are identical, < 0 if this CString object is less than lpsz, or > 0 if this CString object is greater than lpsz.

// example for CString::Compare
CString s1( "abc" );
CString s2( "abd" );
ASSERT( s1.Compare( s2 ) == -1 ); // Compare with another CString.
ASSERT( s1.Compare( "abe" ) == -1 ); // Compare with LPTSTR string.