Top 100 Most Used PHP Functions – Are You Using Them?

By analyzing over 1,900 open‑source PHP projects, the average usage frequency of each function was calculated and the top 100 most‑used functions were identified.

Function Ranking

Function Analysis

The most common functions are string, array and file functions; mathematical functions are rare because they rely on operators.

Many functions have gained new features, e.g., count() now accepts a second argument, dirname() a second argument, and preg_match() / str_replace() can take arrays.

No recently deprecated function appears in the top 100.

The first non‑core extensions are ext/mbstring, followed by ext/curl, gd, filter and iconv. md5 is the only widely used cryptographic function; sha1 ranks second. print_r appears in one‑third of the projects. dirname ranks high due to nested calls like dirname(dirname(dirname())).

Language constructs are not counted as functions, though they remain important.

Some functions are better replaced by operators: array_push, is_object, func_get_arg, chr, call_user_func.

Many calls aim to determine variable types.

Database functions are not listed separately; they are often used via classes.

PHP code tends to read files more than write them; base64 decoding is common.

Key‑based sorting is more frequent than value‑based sorting. file_get_contents is used for reading, fwrite for writing.

Conclusion

If you are learning or using PHP, reviewing the listed 100 functions will help you recognize the most frequently encountered features during development. They are not the only useful functions, but they cover the majority of everyday code.