Benchmarks

This page compares cli20 against CLI11, argparse, cxxopts, and Boost.Program_options across three representative schemas. All benchmark metrics on this page are smaller is better.

• simple: one flag, one option, and one required positional argument.
• many_options: strings, integers, doubles, paths, and enum-like choices.
• subcommand: a small command tree with build and test.

Boost.Program_options is shown as a reference value because it links against the Boost.Program_options shared library. Its binary-size numbers are therefore not directly comparable with the mostly header-only libraries.

Results

Language mode

Runtime

smaller is better

SimpleMany optionsSubcommand

Allocation count

smaller is better

SimpleMany optionsSubcommand

Runtime allocated bytes

smaller is better

SimpleMany optionsSubcommand

Stripped binary size

smaller is better

SimpleMany optionsSubcommand

Compile time

smaller is better

SimpleMany optionsSubcommand

* Boost.Program_options is a reference value: it links against the Boost.Program_options shared library, so binary-size results do not represent a fully self-contained executable in the same way as the header-oriented libraries.

Case	Library	Runtime	Allocs	Bytes	Stripped size	Compile time
Simple	cli20	253.5 ns	0 allocs	0 B	87.3 KiB	1.57 s
Simple	CLI11	3,008.4 ns	81 allocs	4.15 KiB	371.9 KiB	3.74 s
Simple	argparse	1,419 ns	34 allocs	3.47 KiB	120.8 KiB	1.78 s
Simple	cxxopts	9,319.8 ns	330 allocs	21.4 KiB	170.5 KiB	2.08 s
Simple	Boost*	2,788.3 ns	86 allocs	5 KiB	38.2 KiB	0.88 s
Many options	cli20	2,732.9 ns	0 allocs	0 B	211 KiB	2.16 s
Many options	CLI11	17,231.5 ns	503 allocs	22.8 KiB	404.4 KiB	3.51 s
Many options	argparse	5,357.3 ns	98 allocs	13.7 KiB	139.3 KiB	1.82 s
Many options	cxxopts	42,829.3 ns	1,489 allocs	123.5 KiB	187.8 KiB	2.19 s
Many options	Boost*	20,222.5 ns	412 allocs	27 KiB	108.5 KiB	1.14 s
Subcommand	cli20	201 ns	0 allocs	0 B	120.2 KiB	1.59 s
Subcommand	CLI11	3,681.5 ns	107 allocs	6.95 KiB	372.1 KiB	3.26 s
Subcommand	argparse	2,284.8 ns	64 allocs	5.78 KiB	120.9 KiB	1.58 s
Subcommand	cxxopts	2,855.4 ns	105 allocs	7.59 KiB	170.5 KiB	1.8 s
Subcommand	Boost*	960.1 ns	36 allocs	1.71 KiB	37.7 KiB	0.75 s

Benchmark Source

The benchmark code is kept in the repository so every number on this page can be traced back to the parser setup being measured.

Area	Source
Runtime benchmarks	bench/runtime/
Binary size benchmarks	bench/size/
Compile-time benchmarks	bench/compile_time/
Shared argv/allocation helpers	bench/include/bench/
Result summarization	bench/scripts/

Method

Runtime benchmarks construct the parser and parse the same argv every iteration. Allocation counts are measured inside the same operation.

Binary size benchmarks build one executable per library and case, then record both the unstripped and stripped file sizes.

Compile-time benchmarks compile one translation unit per library and case with hyperfine, using the same benchmark source as the binary-size targets.