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Command-Line Arguments with argparse

ArgumentParser declares positional arguments, options, defaults and type conversion. It also generates help text and reports malformed input. Run as a Python 3.11+ script.

Syntax

parser.add_argument("--count", type=int, default=1); parser.parse_args()

Examples

Command-Line Arguments with argparse

Run as a Python 3.11+ script.

import argparse
parser = argparse.ArgumentParser(description="Repeat a greeting")
parser.add_argument("name")
parser.add_argument("--count", type=int, default=1)
args = parser.parse_args(["Ada", "--count", "2"])
for _ in range(args.count):
    print(f"Hello, {args.name}")
  1. Expected output: Hello, Ada Hello, Ada
  2. Passing a list makes the example deterministic. In an actual CLI, parse_args() with no argument reads the process command line.

Best practices

  • Validate domain limits, such as nonnegative counts, after type conversion.
  • Let argparse generate usage errors instead of indexing sys.argv manually.

Runtime & versions

Python interpreter. Feature availability depends on the language and runtime version used by your project; consult the official reference below.

Python language reference

Specifications & further reading