qt开发环境

#include <QCoreApplication>#include <iostream>#include <string>#include <cstring>using namespace std;int main(int argc, char *argv[]){    QCoreApplication a(argc, argv);    //c++的字符串定义    string s1;    cout << '[' << s1 << ']'<< endl;    string s2("ayumi hamasaki");    cout << '[' << s2 << ']'<< endl;    //c字符串和c++字符串，c++支持把c风格的字符串隐式转换为c++风格    string s3 = "字面值mai kuraki";//字面值隐式转换    cout << '[' << s3 << ']'<< endl;    char const* ps = "字符指针mai kuraki";    cout << '[' << ps << ']'<< endl;    s3 = ps;    cout << '[' << s3 << ']'<< endl;    char sa[] = "字符数组mai kuraki";    cout << '[' << sa << ']'<< endl;    cout << strlen(s3.c_str()) << endl;//字符串成员函数，可以获得c的首地址    //字符串的赋值 对应c strcpy    string s4("ayumi hamasaki……");    s3 = s4;    cout << '[' << s3 << ']'<< endl;    //字符串的拼接 对应c strcat    string s5("I love ");    s3 = s5 + s4;    cout << '[' << s3 << ']'<< endl;    //字符串复合赋值    s5 += s3 += s4;//右结合    cout << '[' << s5 << ']'<< endl;    //字符串的比较 ASCII 长度 strcmp    string s6 = "abcd", s7 = "abCd", s8 = "abcde";    cout << (s6 > s7) << endl;    cout << (s6 > s8) << endl;    s6 = "擎天柱";    s7 = "威震天";    s8 = "大黄蜂";//按照编码    cout << (s6 > s7) << endl;    cout << (s6 > s8) << endl;    //下标访问    cout << s4[2] << endl;    //字符串的大小 不包括 /0    cout << s5.size() << endl;    cout << s8.length() << endl;    //判断字符串是否为空    cout << s8.empty() << endl;//0    s8.clear();    cout << s8.empty() << endl;//1    return a.exec();}