008 关于QString的那点事？

a)        组合字符串

QString str1 = "Welcome";

str1 = str1 + " to you!";

 

QString str2 = "Hello";

str2 += " World!";

 

str2.append(str1);

 

QString str3;

str3.sprintf("%s","Welcome");

str3.sprintf("%s","to you! ");

str3.sprintf("%s%s","welcome ","to you!");

 

QString str4;

str4 = QString("%1 was bornin %2. %3").arg("John").arg(1982).arg("Nice to meetyou");

 

         //移除字符串两边的空白字符

         QStringstr5 = "      Welcome \t to \nyou!      ";

str5 = str5.trimmed();

//移除字符串两边的空白字符，使用单个空格字符代替字符串中出现的空白字符

str5=str5.simplified();

b)        查询字符串数据

//判断一个字符串是否以某个字符串开头

QString str6 = "Welcome to you!";

if(true == str6.startsWith("Welcome",Qt::CaseSensitive))

qDebug()<<"true"<<endl;

         //判断一个字符串是否以某个字符串结尾

   if(true == str6.endsWith('!'))

       qDebug()<<"true"<<endl;

         //判断一个指定的字符串是否出现过

         if(true== str6.contains("Welcome"))

       qDebug()<<"true"<<endl;

c)        字符串转换

//QString::toInt()将字符串转换为整形数值，类似的函数还有toDouble()/toFloat()/toLong()/toLongLong()等

QString str7 = "123";

bool ok;

int hex = str7.toInt(&ok,16);//转换成功则ok=true, hex=293

int dec = str7.toInt(&ok,10);//转换成功则ok=true, dec=125

d)        与QbyteArray的转换

QString str8 = " Welcome toyou! ";

QByteArray ba =str8.toLocal8Bit();//返回一个ASCII编码的8位字符串

qDebug()<<ba;

ba = str8.toLatin1();//返回一个UTF-8编码的8位字符串（UTF-8是ASCII码的超集，它支持整个Unicode字符集）

qDebug()<<ba;

ba.append("Hello,World!");

qDebug()<<ba.data();

toLacal8Bit()返回一个系统本地编码的8位字符串