Question

import curses
import pygame as pg


def main(stdscr):
    stdscr.nodelay(1)  # Makes the `getch` method non-blocking.
    # Use `addstr` instead of `print`.
    stdscr.addstr('Press "Esc" to exit...\n')
    command = ''  # Add the entered characters to this string.

    screen = pg.display.set_mode((640, 480))
    clock = pg.time.Clock()
    rect = pg.Rect(300, 100, 30, 50)

    while True:
        for event in pg.event.get():
            if event.type == pg.QUIT:
                return

        inpt = stdscr.getch()  # Here we get the pressed key.
        if inpt == 27:  # Esc
            return
        elif inpt in (ord('\n'), ord('\r')):  # Enter pressed.
            # Check which command was entered and move the rect.
            if command == 'move right':
                rect.x += 20
            elif command == 'move left':
                rect.x -= 20
            command = ''  # Reset the command string.
            stdscr.addstr(2, 0, '{}\n'.format(command))  # Write in the second line.
        elif inpt == 8:  # Backspace
            command = command[:-1]
            stdscr.addstr(2, 0, '{}\n'.format(command))
        elif inpt not in (-1, 0):  # ValueErrors if inpt is -1 or 0.
            command += chr(inpt)  # Concatenate the strings.
            stdscr.addstr(2, 0, '{}\n'.format(command))

        screen.fill((30, 30, 30))
        pg.draw.rect(screen, (0, 120, 250), rect)
        pg.display.flip()
        clock.tick(30)


if __name__ == '__main__':
    pg.init()
    # Use the curses.wrapper to start the program. It handles
    # exceptions and resets the terminal after the game ends.
    curses.wrapper(main)
    pg.quit()

1和100都是int类型，b是char类型，所以不应该导致编译错误？我不明白为什么它会返回＆＃34;版本1＆＃34;。

有人可以向我解释原因吗？

谢谢

Answer 1

在运行时，您的编译器会将int 100转换为double类型，因为您没有其他选择（即另一个重载方法完全接受int，int和{ {1}}）。

换句话说，您的编译器不是抛出char，而是将占用较小大小的RuntimeException转换为占用更多大小的类型（在您的情况下为int）。这是自动执行而不会丢失信息。

这称为Widening Primitive Conversion或自动转化或隐式转化。

为什么这个方法返回输出？

1 个答案: