Right now, I have file.py and it prints the word "Hello" into text.txt.
f = open("text.txt")
f.write("Hello")
f.close()
I want to do the same thing, but I want to print the word "Hello" into a Python file. Say I wanted to do something like this:
f = open("list.py")
f.write("a = 1")
f.close
When I opened the file list.py, would it have a variable a with a value 1? How would I go about doing this?
If you want to append a new line to the end of a file
with open("file.py", "a") as f:
f.write("\na = 1")
If you want to write a line to the beginning of a file try creating a new one
with open("file.py") as f:
lines = f.readlines()
with open("file.py", "w") as f:
lines.insert(0, "a = 1")
f.write("\n".join(lines))
with open("list.py","a") as f:
f.write("a=1")
This is simple as you see. You have to open that file in write and read mode (a). Also with open() method is safier and more clear.
Example:
with open("list.py","a") as f:
f.write("a=1")
f.write("\nprint(a+1)")
list.py
a=1
print(a+1)
Output from list.py:
>>>
2
>>>
As you see, there is a variable in list.py called a equal to 1.
I would recommend you specify opening mode, when you are opening a file for reading, writing, etc. For example:
for reading:
with open('afile.txt', 'r') as f: # 'r' is a reading mode
text = f.read()
for writing:
with open('afile.txt', 'w') as f: # 'w' is a writing mode
f.write("Some text")
If you are opening a file with 'w' (writing) mode, old file content will be removed. To avoid that appending mode exists:
with open('afile.txt', 'a') as f: # 'a' as an appending mode
f.write("additional text")
For more information, please, read documentation.
a = 1in it (assuming you open it in write mode).write("a=1\n").