Qt中 QString 和 int char char*等相互转换

在编写Qt程序过程中经常遇到各种数据类型的转换，故此写下来方便自己和大家的查找。叮！！！

1.QString to char*

QString qstr = "hello";

char* c_char;

QByteArray qba = qstr.toLatin1();

c_char = qba.data();

使用c语言写的客户端，使用Qt写的服务器，还使用到了c 的fork()函数。

2.char* to QString

char* c_char = "world";

QString qstr = QString(QLatin1String(c_char));

补充:

unsigned char chSerialNumber[16];

invalid conversion from 'unsigned char*' to 'const char*'

      QString::fromUtf8((char *)chSerialNumber)

3.int ,float ,double to QString

①正规

int num = 79;

float fnum = 79.99;

QString qnum = QString::number(num); //默认为十进制转换，其他进制转换需显示指定

QString qnum = QString::number(fnum);

QString qhex = QString::number(num,16).toUpper(); //十六进制大写 qhex = 4F

②奇淫巧技~ QString arg 的用法

int num = 79;

QString str = "hello world!";

QString qstr = QString("%1%2").arg(num).arg(str);

4.QString to float double int

QString qint = "100";

QString qfloat = "100.0";

int intNum = qint.toInt();

float floatNum = qfloat.toFloat();

5.QString与QDateTime之间的转换

QString strtime;

QDateTime time;

time = QDateTime::currentDateTime(); //要包含头文件

strtime = time.toString("yyyy-MM-dd hh:mm:ss");

// strtime = "2019-05-16 19:54:17"

6. 毫秒级时间戳实现：

#include <QDateTime>

QDateTime t1 = QDateTime::currentDateTime();

// to time code

QDateTime t2 = QDateTime::currentDateTime();

QString log2 = QString("~~~~~~ Tmerstatus ~~~~~~ %1").arg(variable);
QByteArray b2 = log2.toLatin1();

LOG(char *log);

7. C++ 中 unsigned char 转 float

unsigned char c[4] = {*,*,*,*};

float test = *reinterpret_cast<float*>(&c);

printf("~~~~~~~ zzz ~~~~~~~~~~~ %f ^^^^^^^^^ \n",test);

8. 使用联合体 unsigned char 转 float

 union data_ {float f;unsigned char uc[4];};data_ x_;x_.f = 3.1415926;unsigned char convertRet[4] = { 0 };for(int i=0; i<4; i++)memcpy(&(convertRet[i]), &x_.uc[i], 1);

9. C++ string 转QString

string c_str = “world”;

QString q_str = QString::fromStdString(c_str);

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