Question

我只是编程的初学者，下面是我用python编写的代码，用于保存和编辑文件，但每次运行程序时都会删除以前的保存数据，所以我很困惑为什么呢？＆＃39;发生了什么？

filename = raw_input("Please enter the file name to open it:\n")
doc = open (filename,'w')
print doc.read
text_input = raw_input("Please enter the data you want to enter in file:\n")
if text_input == "":
    print "no input closing the programme."
else :
    doc.write(text_input)
    doc.close()
print "Printing the file:\n"
print doc.read
cl_file = raw_input("do you want to truncate file(y/n): ")
if cl_file == "y":
    doc.truncate()
else :
    print "Wrong input closing notepad"
    exit()

Answer 1

您正在以写入模式打开文件，该文件在写入文件之前截断该文件。而不是使用export Class ChildComponent implements OnInit{ arrayToGet; //An array that I want to pass from Parent to child ngOnInit(){ console.log('The Array I got is ', this.arrayToGet); //Undefined, Tried even with setTimeout } @Input('arrayToGet') set _arrayToGet(data: Array) { this.arrayToGet = data; console.log(this.arrayToGet); } //A bunch of methods to work with the array I get }使用open(filename, 'w')。 'a'值告诉open函数使用append模式，以便将对文件的写入添加到任何现有内容的末尾。

基本Python编程 - 在文件中写入数据

1 个答案: