小编git*_*tha的帖子

我试图理解 python 中的 kivy 库。下面是完整的代码。

import kivy
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.textinput import TextInput
from kivy.uix.button import Button

class MyGrid(GridLayout):
    def __init__(self, **kwargs):
        super(MyGrid, self).__init__(**kwargs)
        self.cols = 1

        self.inside = GridLayout()
        self.inside.cols = 2

        self.inside.name = TextInput(multiline=False)
        self.inside.add_widget(self.inside.name)
        self.inside.add_widget(Label(text="Name: "))

        self.inside.name = TextInput(multiline=False)
        self.inside.add_widget(self.inside.name)
        self.inside.add_widget(Label(text="Email: "))

        self.inside.name = TextInput(multiline=False)
        self.inside.add_widget(self.inside.name)
        self.inside.add_widget(Label(text="Phno: "))

        self.add_widget(self.inside)

        self.submit = Button(text="Submit", font_size=40)
        self.submit.bind(on_press=self.pressed)
        self.add_widget(self.submit)        

    def pressed(self, instance):
        print("pressed")



class MyApp(App):
    def build(self):
        return MyGrid()


if __name__ …

当我们比较字符串/字符格式的数字时，c++ 编译器如何解释它？下面的例子将说明这一点。

#include <iostream>
using namespace std;

int main() {
// your code goes here
    if ('1'<'2')
        cout<<"true";
    return 0;
}

输出是

true

编译器内部发生了什么？是否存在从字符串到整数的隐式转换，就像我们使用字符引用数组中的索引一样，

   arr['a']
=> arr[97]