How to count the number of lines that contain only one comma separated and ignore count the lines with two comma separated in text file

Question

I want to count the number of lines that contain only one comma-separated and ignore count the lines with two comma-separated in a text file

Below is my code

def countLines(filename):
   with open(filename,'r') as f: 
      CoList = f.split("\n") 
      Counter = 0 
      for i in CoList: 
          if i: 
             Counter += 1 
      return CoList

countLines('demo.txt')

Answer 1

I think this is what you want?

def countLines(filename):
    with open(filename,'r') as f: 
        Counter = 0 
        for line in f: 
            if line.count(',') == 1:
                Counter += 1 
      return Counter