需要的头文件和库
#include <imm.h>
#pragma comment (lib ,"imm32.lib")
//切换英文输入法,00000409代表的是系统自带的美式键盘
HKL hkl = LoadKeyboardLayout(_T("00000409"), KLF_ACTIVATE);
PostMessage(hWnd, WM_INPUTLANGCHANGEREQUEST, (WPARAM)TRUE, (LPARAM)hkl);
//切换中文输入法,00000804代表的是智能中文输入法,比如搜狗输入法之类的
hkl = LoadKeyboardLayout(_T("00000804"), KLF_ACTIVATE);
PostMessage(hWnd, WM_INPUTLANGCHANGEREQUEST, (WPARAM)TRUE, (LPARAM)hkl);