Top 100 PHP Functions Every Developer Should Know

The following list showcases the Top 100 PHP functions most commonly used native PHP functions. These functions are ranked from 1 to 100 based on their usage frequency across PHP code repositories. The reference corpus includes a list of 2,500 PHP Open Source projects (top 1,000 Composer packages, public repositories from GitHub/GitLab/Gitee, and downloaded archives). The analysis was conducted using the Exakat static analysis engine, version 2.4.7. The ‘Average’ column indicates how often a function is called within a single project.

For instance, the count() function is used in 4 out of 5 projects and called approximately 61 times per project. It is both popular and heavily used. On the other hand, dirname() is commonly used but less frequently called (used by 56% of projects for about 13 usages).

Clicking on the links will direct you to the documentation for each function. Additional insights are provided at the end of the list.

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Top 100 PHP functions

Here’s a well-formatted table with all the entries preserved:

Rank	Function	Usage %	Count
1	file_exists	66.05%	18
2	count	63.67%	87
3	str_replace	63.58%	51
4	implode	62.72%	48
5	substr	60.30%	70
6	array_merge	60.02%	51
7	sprintf	59.89%	103
8	dirname	58.91%	17
9	explode	58.30%	37
10	in_array	58.27%	49
11	strpos	58.08%	31
12	is_array	58.05%	73
13	strlen	56.37%	45
14	array_key_exists	54.87%	88
15	array_keys	54.72%	23
16	preg_match	52.02%	40
17	file_get_contents	51.76%	11
18	trim	48.49%	37
19	is_string	48.46%	27
20	array_values	48.46%	10
21	is_file	46.90%	7
22	method_exists	46.62%	11
23	array_map	46.11%	17
24	file_put_contents	46.11%	7
25	strtolower	45.44%	26
26	function_exists	44.97%	21
27	preg_replace	44.40%	23
28	defined	43.44%	27
29	is_dir	41.70%	8
30	json_decode	41.54%	10
31	json_encode	41.16%	15
32	call_user_func	41.06%	5
33	array_filter	41.00%	10
34	strtr	40.55%	6
35	fwrite	40.08%	7
36	rtrim	39.85%	8
37	strrpos	39.54%	4
38	call_user_func_array	39.41%	4
39	filter_var	39.25%	3
40	class_exists	39.22%	17
41	header	38.71%	11
42	array_flip	38.62%	3
43	realpath	38.11%	6
44	ini_get	38.01%	6
45	get_class	36.01%	14
46	is_object	35.03%	15
47	unlink	34.96%	8
48	trigger_error	34.84%	8
49	array_shift	34.71%	8
50	is_int	33.76%	7
51	spl_autoload_register	33.57%	1
52	is_numeric	32.93%	13
53	strtoupper	32.93%	9
54	mkdir	32.93%	4
55	array_pop	32.52%	7
56	ltrim	31.95%	5
57	headers_sent	31.95%	2
58	fopen	31.88%	8
59	array_unique	31.79%	6
60	str_repeat	31.47%	9
61	basename	31.25%	6
62	array_slice	30.39%	5
63	fclose	29.91%	7
64	time	29.47%	16
65	is_callable	29.37%	5
66	preg_match_all	29.28%	4
67	is_bool	29.15%	3
68	microtime	28.74%	5
69	spl_autoload_unregister	28.71%	1
70	var_export	28.61%	4
71	array_unshift	28.58%	3
72	max	28.42%	7
73	array_search	28.29%	4
74	apcu_fetch	28.29%	0
75	extension_loaded	28.20%	4
76	getcwd	28.17%	2
77	preg_split	28.14%	4
78	reset	28.10%	6
79	end	28.04%	4
80	gettype	28.04%	4
81	stream_resolve_include_path	27.85%	0
82	md5	27.72%	6
83	getenv	27.66%	6
84	apcu_add	27.41%	0
85	ucfirst	27.34%	7
86	ksort	27.31%	3
87	date	27.18%	14
88	is_null	26.90%	27
89	parse_url	26.61%	3
90	preg_quote	26.61%	4
91	array_reverse	26.58%	3
92	array_diff	26.45%	4
93	base64_encode	26.14%	4
94	version_compare	26.04%	4
95	preg_replace_callback	25.91%	4
96	current	25.25%	3
97	round	25.25%	7
98	min	25.15%	4
99	serialize	25.02%	6

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Insights from the Top 100 PHP Functions

• Common Categories: Most commonly used functions are related to strings, arrays, and file handling.
• Math Functions: Not prominently ranked, as mathematical operations are often handled via operators.
• Database Functions: Functions like pdo, mysqli*, pg_* are mostly handled via classes or components, hence not in the list.
• Deprecation: No recently deprecated functions appear in the top 100.
• Usage of Composer: Some native functions are used less frequently due to popular Composer packages replacing them.
• Crypto Functions: Only md5() appears widely; hash() is ranked 159th (not shown here). This needs improvement for better security practices.
• Debug Functions: Functions like print_r() or var_dump() are not in the top 100; however, var_export() is ambiguously included.
• Type Checking: Functions like is_array(), is_string(), and is_object() are frequently used, highlighting the importance of type validation.
• Operator Replacement: Functions like call_user_func() and call_user_func_array() could be replaced by operators for better performance.

If you are learning PHP, familiarizing yourself with these Top 100 PHP functions is a good idea. They represent the features you’ll encounter most often when working within a PHP coding team.

Would you like me to continue the list from 26 to 100 and enhance the overall presentation?