I need this code in python please
In the Spotlight: Modifying Records Julie is very happy with the programs that you have written so far. Your next job is to write a program that she can use to modify the quantity field in an existing record. This will allow her to keep the records up to date as coffee is sold or more coffee of an existing type is added to inventory. To modify a record in a sequential file, you must create a second temporary file. You copy all of the original file’s records to the temporary file, but when you get to the record that is to be modified, you do not write its old contents to the temporary file. Instead, you write its new modified values to the temporary file. Then, you finish copying any remaining records from the original file to the temporary file. The temporary file then takes the place of the original file. You delete the original file and rename the temporary file, giving it the name that the original file had on the computer’s disk. Here is the general algorithm for your program. Open the original file for input and create a temporary file for output. Get the description of the record to be modified and the new value for the quantity. Read the first description field from the original file. While the description field is not empty: Read the quantity field. If this record’s description field matches the description entered: Write the new data to the temporary file. Else: Write the existing record to the temporary file. Read the next description field. Close the original file and the temporary file. Delete the original file. Rename the temporary file, giving it the name of the original file. Chapter 7 files and Exceptions Notice that at the end of the algorithm you delete the original file and then rename the tem- porary file. The Python standard library’s os module provides a function named remove, that deletes a file on the disk. You simply pass the name of the file as an argument to the function. Here is an example of how you would delete a file named coffee.txt: remove(‘coffee.txt’) The os module also provides a function named rename, that renames a file. Here is an example of how you would use it to rename the file temp.txt to coffee.txt: rename (‘temp.txt’, ‘coffee.txt’) Program 7-18 shows the code for the program. Program 718 (modify_coffee_records.py) 1 2 # This program allows the user to modify the quantity # in a record in the coffee.txt file. import os # Needed for the remove and rename functions def main(): # Create a bool variable to use as a flag. found = False # Get the search value and the new quantity. search = input(‘Enter a description to search for: ‘) new_qty = int(input(‘Enter the new quantity: ‘)) Open the original coffee.txt file. coffee_file = open(‘coffee.txt’, ‘r’) # Open the temporary file. temp_file = open(‘temp.txt’, ‘W’) # Read the first record’s description field. descr = coffee_file.readline() # Read the rest of the file. while descr 1= ”: # Read the quantity field. qty = float(coffee_file.readline()) # Strip the n from the description. descr = descr.rstript’n’) # Write either this record to the temporary file, # or the new record if this is the one that is to be modified. if descr == search: 7.3 Processing Records 273 # Write the modified record to the temp file. temp_file.write( descr + ‘n’) temp_file.write(str(new_qty) + ‘n’) # Set the found flag to True. found = True else: # Write the original record to the temp file. temp_file.write(descr + ‘n’) temp_file.write(str(gty) + ‘n’) # Read the next description. descr = coffee_file.readline() # Close the coffee file and the temporary file. coffee_file.close() temp_file.close() # Delete the original coffee.txt file. os.remove(‘coffee.txt’) # Rename the temporary file. os.rename( ‘temp.txt’, ‘coffee.txt’) # If the search value was not found in the file # display a message. if found: print(‘The file has been updated.’) else: print(“That item was not found in the file.’) 66 # Call the main function. 67 main() Program Output (with input shown in bold) Enter a description to search for: Brazilian Dark Roast Enter Enter the new quantity: 10 Enter The file has been updated. Show transcribed image text In the Spotlight: Modifying Records Julie is very happy with the programs that you have written so far. Your next job is to write a program that she can use to modify the quantity field in an existing record. This will allow her to keep the records up to date as coffee is sold or more coffee of an existing type is added to inventory. To modify a record in a sequential file, you must create a second temporary file. You copy all of the original file’s records to the temporary file, but when you get to the record that is to be modified, you do not write its old contents to the temporary file. Instead, you write its new modified values to the temporary file. Then, you finish copying any remaining records from the original file to the temporary file. The temporary file then takes the place of the original file. You delete the original file and rename the temporary file, giving it the name that the original file had on the computer’s disk. Here is the general algorithm for your program. Open the original file for input and create a temporary file for output. Get the description of the record to be modified and the new value for the quantity. Read the first description field from the original file. While the description field is not empty: Read the quantity field. If this record’s description field matches the description entered: Write the new data to the temporary file. Else: Write the existing record to the temporary file. Read the next description field. Close the original file and the temporary file. Delete the original file. Rename the temporary file, giving it the name of the original file. Chapter 7 files and Exceptions Notice that at the end of the algorithm you delete the original file and then rename the tem- porary file. The Python standard library’s os module provides a function named remove, that deletes a file on the disk. You simply pass the name of the file as an argument to the function. Here is an example of how you would delete a file named coffee.txt: remove(‘coffee.txt’) The os module also provides a function named rename, that renames a file. Here is an example of how you would use it to rename the file temp.txt to coffee.txt: rename (‘temp.txt’, ‘coffee.txt’) Program 7-18 shows the code for the program.
Program 718 (modify_coffee_records.py) 1 2 # This program allows the user to modify the quantity # in a record in the coffee.txt file. import os # Needed for the remove and rename functions def main(): # Create a bool variable to use as a flag. found = False # Get the search value and the new quantity. search = input(‘Enter a description to search for: ‘) new_qty = int(input(‘Enter the new quantity: ‘)) Open the original coffee.txt file. coffee_file = open(‘coffee.txt’, ‘r’) # Open the temporary file. temp_file = open(‘temp.txt’, ‘W’) # Read the first record’s description field. descr = coffee_file.readline() # Read the rest of the file. while descr 1= ”: # Read the quantity field. qty = float(coffee_file.readline()) # Strip the n from the description. descr = descr.rstript’n’) # Write either this record to the temporary file, # or the new record if this is the one that is to be modified. if descr == search: 7.3 Processing Records 273 # Write the modified record to the temp file. temp_file.write( descr + ‘n’) temp_file.write(str(new_qty) + ‘n’) # Set the found flag to True. found = True else: # Write the original record to the temp file. temp_file.write(descr + ‘n’) temp_file.write(str(gty) + ‘n’) # Read the next description. descr = coffee_file.readline() # Close the coffee file and the temporary file. coffee_file.close() temp_file.close() # Delete the original coffee.txt file. os.remove(‘coffee.txt’) # Rename the temporary file. os.rename( ‘temp.txt’, ‘coffee.txt’) # If the search value was not found in the file # display a message. if found: print(‘The file has been updated.’) else: print(“That item was not found in the file.’) 66 # Call the main function. 67 main() Program Output (with input shown in bold) Enter a description to search for: Brazilian Dark Roast Enter Enter the new quantity: 10 Enter The file has been updated.
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