Python Files Input Output Functions

Programs often need to read data from a file or save results for later, and Python's built-in file handling functions make this straightforward, whether you're loading a dataset or writing out a report.

Opening a File

The open() function is used to open a file in a particular mode, such as read ("r"), write ("w"), or append ("a").

file = open("data.txt", "r")
content = file.read()
file.close()

Reading Files Line by Line

file = open("data.txt", "r")
for line in file:
    print(line.strip())
file.close()

Writing to a File

file = open("output.txt", "w")
file.write("Result: 42\n")
file.close()

Using the with Statement

The with statement opens a file and automatically closes it once you're done, even if an error occurs while working with it.

with open("data.txt", "r") as file:
    content = file.read()
print(content)

In data science workflows, file handling is used constantly to load raw datasets and to save processed results, logs, or trained model outputs, so using with is considered best practice.

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