QString str = “我是中国人123”；
char gbk[64];
QByteArray ba = QTextCodec::codecForName(“GBK”)->fromUnicode(str);//unicodezhuangGBK之间的转换器
memset(gbk, 0, sizeof(gbk));//初始化为0
strcpy(gbk, ba.data());
const char *str_2 = gbk;
int str_len = strlen(str_2);//获取转换长度
printf(“str_len = %d \n”, str_len);
输出结果：str_len = 13;