一、把字符串转换成整形

demo1:

QString str = "FF";

bool ok;

int hex = str.toInt(&ok, 16); // hex == 255, ok == true

int dec = str.toInt(&ok, 10); // dec == 0, ok == false

demo2:

bool ok;

QString line = "123";

int line1 = line.toInt(&ok); //把字符串“123”转换成整形的123

二、把整形转换成字符串

demo1：

long a = 63;

QString s = QString::number(a, 16); // s == "3f"

QString t = QString::number(a, 16).toUpper(); // t == "3F"

demo2：

int line4 = 123;

QString line4_4;

line4_4 = QString::number(line4);  //把整形的123转换成字符串的"123"

三、获取输入对象中的字符串

QString line2 = ui->line1->text();

//line1为输入对象,把line1中的字符串保存在line2中

四、设置输入对象中的字符串

ui->line4->setText("hello");

//输入框中显示"hello"

 

使用例子：根据输入的运算符号进行两个数的加减乘除运算，让后点击一下按钮自动进行运算。

头文件：mainwindow.h

 

1 #ifndef MAINWINDOW_H 2 #define MAINWINDOW_H 3  4 #include 
     
       5  6 namespace Ui { 7 class MainWindow; 8 } 9 10 class MainWindow : public QMainWindow11 {12     Q_OBJECT13 14 public:15     explicit MainWindow(QWidget *parent = 0);16     ~MainWindow();17 18 private slots:19     void on_jieguo_clicked(); //槽函数，不懂的话可以看看我这篇的20 21 private:22     Ui::MainWindow *ui;23 };24 25 #endif // MAINWINDOW_H
     

 

源文件：mainwindow.cpp

1 #include "mainwindow.h" 2 #include "ui_mainwindow.h" 3 #include 
     
       4 #include 
      
        5 #include 
       
         6 #include 
        
          7 #include 
         
           8  9 MainWindow::MainWindow(QWidget *parent) :10     QMainWindow(parent),11     ui(new Ui::MainWindow)12 {13     ui->setupUi(this);14     //建立槽连接15     connect(ui->jieguo,SIGNAL(clicked(bool)),this,SLOT(MainWindow::on_jieguo_clicked()));16 }17 18 MainWindow::~MainWindow()19 {20     delete ui;21 }22 23 void MainWindow::on_jieguo_clicked()24 {25        QString line1 = ui->line1->text();//读出输入到line1中的字符串26        QString line2 = ui->line2->text();27        QString line3 = ui->line3->text();28        QString line5;29 30        bool ok;31        int line4_4 = 0;32        int line1_1;33        int line3_3;34        line1_1 = line1.toInt(&ok); //把字符转换成整形35        line3_3 = line3.toInt(&ok);36        if(!ok)37        {38           return;39        }40        else if(line2 == "+")41         {42             line4_4 = line1_1 + line3_3;43         }44 45        else if(line2 == "-")46         {47             line4_4 = line1_1 - line3_3;48         }49 50        else if(line2 == "*")51         {52             line4_4 = line1_1* line3_3;53         }54 55         else if(line2 == "/")56         {57             if(line3_3 != 0)58             {59                 line4_4 = line1_1 / line3_3;60             }61             else62             {63                 line4_4 = 0;64             }65 66         }67         ui->line4->setText(QString::number(line4_4));//QString::number把整形转化成字符68         line5 = ui->line4->text();69         qDebug()<
         
        
       
      
     

 

界面文件如下：