The 100 PHP functions that you have to know
Here is the top 100 PHP functions : it is the list of the most often used PHP native functions.
The functions are named, and ranked from 1 to 100. The other 4500 functions are not ranked here. The frequency column represents how often this function is used across PHP code repositories : the reference corpus is a list of 2500 PHP Open Source projects (top 1000 composer, github/gitlab/gitee public repo, downloaded archives…). They were audited with Exakat static analysis engine, version 2.4.7. The average is the number of time the function is called within one project.
For example, 4 project out of 5 uses the count() function, and when used, count() is called around 61 times. It is both a popular and heavily used function. On the other hand, dirname() is popular but rarely used (56% for 13 usages)
Click on the link to go to the documentation. Some insight at the bottom of the top 100.
The 100 most popular PHP functions
| 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 |
Top 100 insights
- The most commonly used PHP functions are string functions, and then arrays, then files.
- Math functions are probably out of the ranking, as they are mostly based on operators
- Databases functions (pdo, mysqli*, pg_*…) are probably out of scope, as they are based on classes or components
- No recently deprecated function is in the top 100.
- Usage of composer may also reduce the need for some native function, by federating them in a component, and reducing their overall usage. For example, monolog may use log() and reduce its usage across the Open Source community.
- Extension that makes it to the top 100 : filter, json, apcu.
- json_encode() and json_decode() are now used with the same exact frequency, or almost.
md5is the only widely used crypto function. hash() is the next, in 159th position (not shown). This must change!- Debug functions, such as print_r() or var_dump() are out of the top 100. var_export() is a more ambiguous case.
array,echo,print,empty,issetand other language constructs were not counted as functions in this ranking. They are probably trusting the first ranks anyway.- Several functions could and should be replaced by operators :
is_object(), call_user_func(), call_user_func_array() - max() is more often than min()
- Types are still a major concern of PHP code : is it a string? is it an object? No, it’s a resource!
- Type system may go a long way, but there are still return values that needs testing.
- There is also a PHP top 100 for the PHP classes. Well,
Challenges
If you are learning PHP, it is a good idea to review the 100 functions ranked here : they are the features you’ll find the most often when landing on a coding team. They are not the only ones, but you’ll be less surprised when meeting them.
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