Python - for 循環內的變量在循環外消失

Question

編輯：如果您也遇到過這個問題，下面有兩種可能的解決方案。

我正在制作一個非常簡單的 Python 腳本來合並幾個 markdown 文件，同時保留所有換行符。 我要合並的文件稱為markdown/simple1.md 、 markdown/simple2.md和markdown/simple3.md （它們位於名為markdown/的文件夾中。

這是simple1.md的文本內容：

Page 1

This is some useless content

這是simple2.md的文本內容：

Page 2

This is some useless content

這是simple3.md的文本內容：

Page 3

This is some useless content

這是我到目前為止所擁有的：

# Define files I want to merge

filenames = ['markdown/simple1.md', 'markdown/simple2.md', 'markdown/simple3.md']

# Merge markdown files into one big file

merged_filecontent = ""
file = ""

for file in filenames:
  file = open(file).read()
  file += "\n"
  # print(file)
  merged_filecontent = file
  print(merged_filecontent)

這完美地工作。 但是，一旦我嘗試在for循環之外調用變量，如下所示：

# Define files I want to merge

filenames = ['markdown/simple1.md', 'markdown/simple2.md', 'markdown/simple3.md']

# Merge markdown files into one big file

merged_filecontent = ""
file = ""

for file in filenames:
  file = open(file).read()
  file += "\n"
  # print(file)
  merged_filecontent = file
  
# Call variable outside of for loop

print(merged_filecontent)

該變量僅返回第 3 個 markdown 文件，並且不顯示合並后的文件。

我將不勝感激有關此問題的任何幫助。

Answer 1

您正在循環內重新聲明file變量。 嘗試：

filenames = ['markdown/simple1.md', 'markdown/simple2.md', 'markdown/simple3.md']
merged_filecontent = ""

for file in filenames:
  with open(file) as f:
    merged_filecontent += f.read()+"\n"

print(merged_filecontent)

Answer 2

您實際上需要將文件內容與merged_filecontent += file合並

# Define files I want to merge

filenames = ['markdown/simple1.md', 'markdown/simple2.md', 'markdown/simple3.md']

# Merge markdown files into one big file

merged_filecontent = ""
file = ""

for file in filenames:
  file = open(file).read()
  file += "\n"
  # print(file)
  merged_filecontent += file
  
# Call variable outside of for loop

print(merged_filecontent)