This function returns the length in bytes (ANSI version) or WCHAR values (Unicode version) of the specified string (not including the terminating null character).

Syntax

int lstrlen(      
    LPCTSTR lpString
);

Parameters

lpString

[in] Pointer to a null-terminated string.

Return Value

The return value specifies the length of the string, in TCHAR values. This refers to bytes for ANSI versions of the function or WCHAR values for Unicode versions. If lpString is NULL, the return value is 0.

Remarks

Security Alert  

Using this function incorrectly can compromise the security of your application. lstrlen assumes that lpString is a null-terminated string, or NULL. If it is not, this could lead to a buffer overrun or a denial of service attack against your application.

Consider using one of the following alternatives: StringCbLength or StringCchLength.

Review Security Considerations: Windows User Interface before continuing.

Windows 95/98/Me: Although lstrlenW exists on Microsoft Windows 95/98/Me, it is supported by the Microsoft Layer for Unicode (MSLU) to give more consistent behavior across all Windows operating systems. To use this, you must add certain files to your application, as outlined in Microsoft Layer for Unicode on Windows 95/98/Me Systems.

Example

For an example, see Displaying Keyboard Input.

Function Information

Minimum DLL Version	kernel32.dll
Header	Declared in Winbase.h, include Windows.h
Import library	Kernel32.lib
Minimum operating systems	Windows 95, Windows NT 3.1
Unicode	Implemented as ANSI and Unicode versions.

See Also

Strings Overview, StringCbLength, StringCchLength, lstrcat, lstrcmp, lstrcmpi, lstrcpy