wcstombs示例：

/* wcstombs example */
#include <stdio.h>      /* printf */
#include <stdlib.h>     /* wcstombs, wchar_t(C) */

int main() {
  const wchar_t str[] = L"wcstombs example";
  char buffer[32];
  int ret;

  printf ("wchar_t string: %ls \n",str);

  ret = wcstombs ( buffer, str, sizeof(buffer) );
  if (ret==32) buffer[31]='\0';
  if (ret) printf ("multibyte string: %s \n",buffer);

  return 0;
}

输出：

• wchar_t string: wcstombs example
• multibyte string: wcstombs example

	//mbstowcs == multibyte string to wide character string
	int requiredSize = mbstowcs(NULL, string, 0);    //如果mbstowcs第一参数为NULL那么返回字符串的数目  requiredSize为string转为宽字符后的宽字符字符数，注意这个数目不包含结尾符
	wchar_t* wText = new wchar_t[requiredSize + 1];    //+1以保留一个位置放置结尾符 0/
	mbstowcs(wText, string, requiredSize + 1);//由char转换成wchar类型