Read a file in Python

.read() reads the whole file into one string. This is the simplest way to read a file, and it is fine for small and medium files.

The program

# create a small file first, so there is something to read
with open("poem.txt", "w", encoding="utf-8") as f:
    f.write("Roses are red,\nViolets are blue,\nPython is fun,\nAnd so are you.\n")

with open("poem.txt", encoding="utf-8") as f:
    content = f.read()

print(content, end="")
print("Characters:", len(content))

Roses are red,
Violets are blue,
Python is fun,
And so are you.
Characters: 64

How it works

• open("poem.txt") opens the file in read mode. Read mode ("r") is the default, so you do not need to write it.
• content is one string. The line breaks are inside it as \n characters, and each one counts as a character in len(content).
• The file is closed when the with block ends. content is still available after that, because it is a normal string in memory.

When the file is missing

If the file does not exist, open() raises FileNotFoundError. Catch it to show a clear message instead of a traceback:

filename = "missing.txt"

try:
    with open(filename, encoding="utf-8") as f:
        content = f.read()
except FileNotFoundError:
    print(f"Could not find {filename}")

Could not find missing.txt

For a very large file (for example a log file of several gigabytes), read() would load all of it into memory. Read it line by line instead.