7-2【任务7-2】实现文件内容的写入与读取

【任务7-2】实现文件内容的写入与读取【任务描述】（1）在项目Unit07创建Python程序文件7-2.py。（2）使用两种方法将图书数据写入当前工作文件夹的

“myBook.txt”文件中。（3）使用两种方法从“myBook.txt”文件中

读取全部行，并输出。【任务实施】1．创建Python程序文件7-2.py在PyCharm项目“Unit07”中，新建Python程序文件“7-2.py”，同时PyCharm主窗口显示程序文件“7-2.py”的代码编辑窗口，在该程序文件的代码编辑窗口也自动添加了模板内容。【任务实施】2．编写Python程序代码在新建文件“7-2.py”的代码编辑窗口已有模板注释内容下面输入程序代码。【任务实施】fieldName=["商品编码","图书名称","价格"]book=["book1","book2","book3"]book1=["12528944","PPT设计从入门到精通",79.00]book2=["12563157","给Python点颜色青少年学编程",59.80]book3=["12451724","Python从入门到项目实践（全彩版）",99.80]book4=["12550531","Python编程锦囊（全彩版）",79.80]【任务实施】defgetSize(text):iftype(text)!=str:text=str(text)lenText=len(text)#调用len函数计算字符串的字符数量

lenTextUtf8=len(text.encode('UTF-8'))#计算字符串UTF-8编码的长度

iflenText!=lenTextUtf8:size=int(lenText-(lenTextUtf8-lenText)/2)#计算字符中半角字符的数量

returnsizeelse:return0【任务实施】defwriteFile1():objFile=open(r"D:\PycharmProject\Unit07\myBook.txt","w")objFile.write("{0:{1}^6s}".format(fieldName[0],chr(12288)))objFile.write("{0:{1}^18s}".format(fieldName[1],chr(12288)))objFile.write("{0:{1}^10s}".format(fieldName[2],chr(12288)))objFile.write("\n")【任务实施】

#使用eval方法将字符串转换为变量名

foritemBookinbook:objFile.write("{0:{1}^10}".format(eval(itemBook)[0],chr(12288)))objFile.write("{0:{1}<20s}".format(eval(itemBook)[1],chr(12288)))objFile.write("{0:<{1}s}".format(chr(32),str(getSize(eval(itemBook)[1]))))objFile.write("{0:{1}>6.2f}".format(eval(itemBook)[2],chr(12288)))objFile.write("\n")objFile.close()【任务实施】defwriteFile2():objFile=open(r"D:\PycharmProject\Unit07\myBook.txt","a")

#使用eval方法将字符串转换为变量名objFile.write("{0:{1}^10}".format(book4[0],chr(12288)))

objFile.write("{0:{1}<20s}".format(book4[1],chr(12288)))objFile.write("{0:<{1}s}".format(chr(32),str(getSize(book4[1]))))objFile.write("{0:{1}>6.2f}".format(book4[2],chr(12288)))objFile.write("\n")【任务实施】defreadFile1():objFile=open(r"D:\PycharmProject\Unit07\myBook.txt","r")strText=""whileTrue:str=objFile.readline()ifstr!="":strText=strText+strelse:breakprint(strText)objFile.close()【任务实施】defreadFile2():withopen(r"D:\PycharmProject\Unit07\myBook.txt","r")asobjFile:fortxtLineinobjFile.readlines():print(txtLine,end="")objFile.close()【任务实施】try:writeFile1()writeFile2()readFile1()readFile2()exceptExceptionaserror:print(error)单击工具栏中【保存】按钮，保存程序文件“7-2.py”。【任务实施】

3．运行