python check if file contains string code example

Example 1: file exist python

import os.path

if os.path.exists('filename.txt'):
    print ("File exist")
else:
    print ("File not exist")

Example 2: python check if file has content

>>> import os
>>> os.stat("file").st_size == 0
True

Example 3: python check if file exists

#using pathlib
from pathlib import Path

file_name = Path("file.txt")
if file_name.exists():
    print("exists") 
else:
    print("does not exist")

Example 4: how to check if a string is in a file python

def search_string_in_file(file_name, string_to_search):
    """Search for the given string in file and return lines containing that string,
    along with line numbers"""
    line_number = 0
    list_of_results = []
    # Open the file in read only mode
    with open(file_name, 'r') as read_obj:
        # Read all lines in the file one by one
        for line in read_obj:
            # For each line, check if line contains the string
            line_number += 1
            if string_to_search in line:
                # If yes, then add the line number & line as a tuple in the list
                list_of_results.append((line_number, line.rstrip()))
 
    # Return list of tuples containing line numbers and lines where string is found
    return list_of_results

Example 5: python read text file look for string

f = open(filename,  "r")
   whattoReturn = "None"
   if strToFind in f.read():
      whattoReturn = strToFind