树莓派终端运行Python脚本时print命令输出带括号问题求助

Hey there! Let's unpack what's going on here—this is a super common mix-up with Python versions, especially on Raspberry Pi which usually has both Python 2 and Python 3 pre-installed.

The Root Cause: You're Running Python 2 Instead of Python 3 #

Here's why you're seeing those unexpected behaviors:

1. Tuple-style output
   In Python 3, print() is a built-in function, so when you write print(num, "is a prime number"), it prints the values separated by spaces (like 5 is a prime number). But in Python 2, print is a statement, not a function. When you use parentheses with the print statement in Python 2, it treats the contents as a single tuple object—hence the output (5, 'is a prime number').

2. Print works without parentheses
   Again, this is Python 2 behavior. In Python 2, the print statement doesn't require parentheses (e.g., print "Hello world" is perfectly valid). In Python 3, omitting parentheses would throw a syntax error because print is strictly a function there.

How to Fix It #

Follow these steps to get the expected behavior:

• Check your Python versions
  Run these commands in your terminal to confirm which versions are installed:

  python --version
  python3 --version
  

  You'll likely see that python points to Python 2.x, while python3 points to Python 3.x.

• Run your script with Python 3
  Instead of using python your_script.py, use:

  python3 your_script.py
  

  This will execute your code with Python 3, where print() acts as a function and gives you the clean output 5 is a prime number.

• Make it permanent with a shebang line
  Add this line at the very top of your Python script:

  #!/usr/bin/env python3
  

  Then give the script executable permissions:

  chmod +x your_script.py
  

  Now you can run it directly with ./your_script.py, and it will automatically use Python 3.

内容的提问来源于stack exchange，提问作者Josh B