how to use concatenate a fixed string and a variable in Python

Question

I want to include file name 'main.txt' in the subject for that I am passing file name from command line. but getting error in doing so

python sample.py main.txt #running python with argument 

msg['Subject'] = "Auto Hella Restart Report "sys.argv[1]  #line where i am using that passed argument

Answer 1

I'm guessing that you meant to do this:

msg['Subject'] = "Auto Hella Restart Report " + sys.argv[1]
# To concatenate strings in python, use       ^ 

Answer 2

variable=" Hello..."  
print (variable)  
print("This is the Test File "+variable)  

for integer type ...

variable="  10"  
print (variable)  
print("This is the Test File "+str(variable))  

Answer 3

我知道这有点旧，但我想用 Python 3.6 版中引入的 f-strings 添加一个更新的答案：

msg['Subject'] = f'Auto Hella Restart Report {sys.argv[1]}'

Answer 4

Try:

msg['Subject'] = "Auto Hella Restart Report " + sys.argv[1]

The + operator is overridden in python to concatenate strings.

Answer 5

If you need to add two strings you have to use the '+' operator

hence

msg['Subject'] = 'your string' + sys.argv[1]

and also you have to import sys in the beginning

as

import sys

msg['Subject'] = "Auto Hella Restart Report " + sys.argv[1]

Answer 6

使用 python 3.6+：

msg['Subject'] = f"Auto Hella Restart Report {sys.argv[1]}"