| addcslashes() | Adds backslashes before specified characters in a given string. |
| addslashes() | Returns a string with backslashes before predefined characters like single quotes, double quotes, backslashes, and NULL. |
| bin2hex() | Converts binary data into a hexadecimal representation. |
| chop() | Alias for rtrim(). Removes whitespace or other specified characters from the end of a string. |
| chr() | Returns a character from the specified ASCII value. |
| chunk_split() | Splits a string into smaller chunks of a specific length, adding a separator (such as a newline). |
| convert_uudecode() | Decodes a uuencoded string. |
| convert_uuencode() | Encodes a string using the uuencode algorithm, typically used for transferring binary data over networks. |
| count_chars() | Returns information about the frequency of every byte (ASCII character) in a string. |
| crc32() | Calculates a 32-bit CRC (cyclic redundancy checksum) for error-checking data integrity. |
| PHP crypt() | Encrypts a string using one-way DES, Blowfish, or MD5 hashing. |
| password_hash() | Creates a password hash using one of several hashing algorithms, returning a hashed string. |
| echo | Outputs one or more strings directly to the browser. |
| explode() | Splits a string into an array by a specified delimiter. |
| hex2bin() | Decodes a hexadecimal string into its binary representation. |
| implode() | Joins array elements into a string, using a specified separator. |
| join() | Alias for implode(). Joins array elements into a string. |
| lcfirst() | Converts the first character of a string to lowercase. |
| levenshtein() | Calculates the Levenshtein distance between two strings, measuring the difference between them. |
| ltrim() | Removes whitespace or specified characters from the beginning of a string. |
| md5_file() | Generates the MD5 hash of a file. |
| md5() | Computes the MD5 hash of a string. |
| metaphone() | Returns the metaphone key (phonetic algorithm) of a string, used for phonetic comparisons. |
| nl2br() | Inserts HTML <br> tags before all newlines in a string. |
| number_format() | Formats a number with grouped thousands and customizable decimal places. |
| ord() | Returns the ASCII value of the first character of a string. |
| parse_str() | Parses a query string into variables. |
| quoted_printable_decode() | Decodes a quoted-printable encoded string into an 8-bit string. |
| quoted_printable_encode() | Converts an 8-bit string to a quoted-printable encoded string. |
| quotemeta() | Adds a backslash in front of characters that have special meanings in regular expressions. |
| rtrim() | Removes whitespace or specified characters from the right end of a string. |
| sha1_file() | Calculates the SHA-1 hash of a file. |
| sha1() | Computes the SHA-1 hash of a string. |
| similar_text() | Calculates the similarity between two strings as a percentage. |
| soundex() | Returns the Soundex key of a string for phonetic comparison. |
| str_pad() | Pads a string to a certain length with another string. |
| str_repeat() | Repeats a string a specified number of times. |
| str_replace() | Replaces all occurrences of the search string with a replacement in the subject string. |
| str_rot13() | Applies the ROT13 encoding, shifting every alphabetic character by 13 places. |
| str_shuffle() | Randomly shuffles the characters of a string. |
| str_split() | Splits a string into an array, with each element being a substring of a specified length. |
| str_word_count() | Returns the number of words in a string, or optionally returns an array of the words. |
| strcasecmp() | Case-insensitive comparison of two strings. |
| strchr() | Finds the first occurrence of a string in another string (alias of strstr()). |
| strcmp() | Compares two strings in a case-sensitive manner. |
| strcoll() | Locale-based string comparison. |
| strcspn() | Returns the length of a segment in a string that doesn't contain specified characters. |
| strip_tags() | Strip HTML and PHP tags from a string. |
| stripos() | Finds the position of the first occurrence of a substring in a string (case-insensitive). |
| stripslashes() | Removes backslashes added by addslashes(). |
| stristr() | Case-insensitive version of strstr(), finds the first occurrence of a substring. |
| strlen() | Returns the length of a string. |
| strnatcasecmp() | Case-insensitive "natural order" string comparison, where numbers are compared numerically. |
| strnatcmp() | "Natural order" string comparison, where numbers are compared numerically. |
| strncasecmp() | Case-insensitive comparison of the first n characters of two strings. |
| strncmp() | Compares the first n characters of two strings in a case-sensitive manner. |
| strpbrk() | Searches a string for any of a set of specified characters. |
| strpos() | Finds the position of the first occurrence of a substring in a string (case-sensitive). |
| strrchr() | Finds the last occurrence of a character in a string. |
| strrev() | Reverses a string. |
| strripos() | Finds the position of the last occurrence of a string (case-insensitive). |
| strrpos() | Finds the position of the last occurrence of a string (case-sensitive). |
| strspn() | Returns the length of the initial segment of a string that contains only specified characters. |
| strstr() | Finds the first occurrence of a substring in a string (alias of strchr()). |
| strtok() | Tokenizes a string into smaller parts based on specified delimiters. |
| strtolower() | Converts a string to lowercase. |
| strtoupper() | Converts a string to uppercase. |
| strtr() | Translates certain characters in a string with other characters. |
| substr_compare() | Compares two strings from a specified start position up to a specified length. |
| substr_count() | Counts the number of occurrences of a substring within a string. |
| substr_replace() | Replaces a part of a string with another string, starting at a specified position. |
| substr() | Returns a portion of a string starting at a specified index. |
| trim() | Removes whitespace or other specified characters from both ends of a string. |
| ucfirst() | Converts the first character of a string to uppercase. |
| ucwords() | Converts the first character of each word in a string to uppercase. |
| vprintf() | Outputs a formatted string using an array of values. |
| vsprintf() | Returns a formatted string using an array of values. |
| wordwrap() | Wraps a string to a specified width using a string break character. |