temp.readline（）为空？

Question

I'm able to create and write to a temp file, however when reading the file lines are empty. I confirmed temp file has content. Here is my code. Thanks

import tempfile
temp = tempfile.NamedTemporaryFile()

with open("~/somefile.txt") as inf:
    for line in inf:
        if line==line.lstrip():
            temp.write(line)

line = str(temp.readline()).strip()
print line #nothing

Answer 1

You have to re-open (or rewind) the temp file before you can read from it:

import tempfile
temp = tempfile.NamedTemporaryFile()

with open("~/somefile.txt") as inf:
    for line in inf:
        if line==line.lstrip():
            temp.write(line)

temp.seek(0) # <=============== ADDED

line = str(temp.readline()).strip()
print line

Otherwise, the file pointer is positioned at the end of the file when you call temp.readline() .