A string is a sequence of characters, like "Hello world!".
PHP String Functions
In this chapter we will look at some commonly used functions to manipulate strings.
strlen[] - Return the Length of a String
The PHP strlen[] function returns the length of a string.
Example
Return the length of the string "Hello world!":
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str_word_count[] - Count Words in a String
The PHP str_word_count[] function counts the number of words in a string.
Example
Count the number of word in the string "Hello world!":
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strrev[] - Reverse a String
The PHP strrev[] function reverses a string.
Example
Reverse the string "Hello world!":
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strpos[] - Search For a Text Within a String
The PHP strpos[] function searches for a specific text within a string. If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE.
Example
Search for the text "world" in the string "Hello world!":
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Tip: The first character position in a string is 0 [not 1].
str_replace[] - Replace Text Within a String
The PHP str_replace[] function replaces some characters with some other characters in a string.
Example
Replace the text "world" with "Dolly":
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Complete PHP String Reference
For a complete reference of all string functions, go to our complete PHP String Reference.
The PHP string reference contains description and example of use, for each function!
PHP Exercises
PHP provides various string functions to access and manipulate strings.
A list of PHP string functions are given below.
addcslashes[]
It is used to return a string with backslashes.
addslashes[]
It is used to return a string with backslashes.
bin2hex[]
It is used to converts a string of ASCII characters to hexadecimal values.
chop[]
It removes whitespace or other characters from the right end of a string
chr[]
It is used to return a character from a specified ASCII value.
chunk_split[]
It is used to split a string into a series of smaller parts.
convert_cyr_string[]
It is used to convert a string from one Cyrillic character-set to another.
convert_uudecode[]
It is used to decode a uuencoded string.
convert_uuencode[]
It is used to encode a string using the uuencode algorithm.
count_chars[]
It is used to return information about characters used in a string.
crc32[]
It is used to calculate a 32-bit CRC for a string.
crypt[]
It is used to create hashing string One-way.
echo[]
It is used for output one or more strings.
explode[]
It is used to break a string into an array.
fprint[]
It is used to write a formatted string to a stream.
get_html_translation_table[]
Returns translation table which is used by htmlspecialchars[] and htmlentities[].
hebrev[]
It is used to convert Hebrew text to visual text.
hebrevc[]
It is used to convert Hebrew text to visual text and new lines [\n] into
.
hex2bin[]
It is used to convert string of hexadecimal values to ASCII characters.
htmlentities[]
It is used to convert character to HTML entities.
html_entity_decode[]
It is used to convert HTML entities to characters.
htmlspecialchars[]
Converts the special characters to html entities.
htmlspecialchars_decode[]
Converts the html entities back to special characters.
Implode[]
It is used to return a string from the elements of an array.
Join[]
It is the Alias of implode[] function.
Levenshtein[]
It is used to return the Levenshtein distance between two strings.
Lcfirst[]
It is used to convert the first character of a string to lowercase.
localeconv[]
Get numeric formatting information
ltrim[]
It is used to remove whitespace from the left side of a string.
md5[]
It is used to calculate the MD5 hash of a string.
md5_files[]
It is used to calculate MD5 hash of a file.
metaphone[]
It is used to calculate the metaphone key of a string.
money_format[]
It is used to return a string formatted as a currency string.
nl2br[]
It is used to insert HTML line breaks in front of each newline in a string.
nl_langinfo[]
Query language and locale information
number_format[]
It is used to format a number with grouped thousands.
ord[]
It is used to return ASCII value of the first character of a string.
parse_str[]
It is used to parse a query string into variables.
print[]
It is used for output one or more strings.
printf[]
It is used to show output as a formatted string.
quoted_printable_decode[]
Converts quoted-printable string to an 8-bit string
quoted_printable_encode[]
Converts the 8-bit string back to quoted-printable string
quotemeta[]
Quote meta characters
rtrim[]
It is used to remove whitespace from the right side of a string.
setlocale[]
It is used to set locale information.
sha1[]
It is used to return the SHA-1 hash of a string.
sha1_file[]
It is used to return the SHA-1 hash of a file.
similar_text[]
It is used to compare the similarity between two strings.
Soundex[]
It is is used to calculate the soundex key of a string.
sprintf[]
Return a formatted string
sscanf[]
It is used to parse input from a string according to a format.
strcasecmp[]
It is used to compare two strings.
strchr[]
It is used to find the first occurrence of a string inside another string.
strcmp[]
Binary safe string comparison [case-sensitive]
strcoll[]
Locale based binary comparison[case-sensitive]
strcspn[]
It is used to reverses a string.
stripcslashes[]
It is used to unquote a string quoted with addcslashes[].
stripos[]
It is used to return the position of the first occurrence of a string inside another string.
stristr[]
Case-insensitive strstr
strlen[]
It is used to return the length of a string.
strncasecmp[]
Binary safe case-insensitive string comparison
strnatcasecmp[]
It is used for case-insensitive comparison of two strings using a "natural order" algorithm
strnatcmp[]
It is used for case-sensitive comparison of two strings using a "natural order" algorithm
strncmp[]
It is used to compare of the first n characters.
strpbrk[]
It is used to search a string for any of a set of characters.
strripos[]
It finds the position of the last occurrence of a case-insensitive substring in a string.
strrpos[]
It finds the length of the last occurrence of a substring in a string.
strpos[]
It is used to return the position of the first occurrence of a string inside another string.
strrchr[]
It is used to find the last occurrence of a string inside another string.
strrev[]
It is used to reverse a string.
strspn[]
Find the initial length of the initial segment of the string
strstr[]
Find the occurrence of a string.
strtok[]
Splits the string into smaller strings
strtolower[]
Convert the string in lowercase
strtoupper[]
Convert the strings in uppercase
strtr[]
Translate certain characters in a string or replace the substring
str_getcsv[]
It is used to parse a CSV string into an array.
str_ireplace[]
It is used to replace some characters in a string [case-insensitive].
str_pad[]
It is used to pad a string to a new length.
str_repeat[]
It is used to repeat a string a specified number of times.
str_replace[]
It replaces all occurrences of the search string with the replacement string.
str_rot13[]
It is used to perform the ROT13 encoding on a string.
str_shuffle[]
It is used to randomly shuffle all characters in a string.
str_split[]
It is used to split a string into an array.
strcoll[]
It is locale based string comparison.
strip_tags[]
It is used to strip HTML and PHP tags from a string.
str_word_count[]
It is used to count the number of words in a string.
substr[]
Return the part of a string
substr_compare[]
Compares two strings from an offset up to the length of characters. [Binary safe comparison]
substr_count[]
Count the number of times occurrence of a substring
substr_replace[]
Replace some part of a string with another substring
trim[]
Remove whitespace or other characters from the beginning and end of the string.
ucfirst[]
Make the first character of the string to uppercase
ucwords[]
Make the first character of each word in a string to uppercase
vfprintf[]
Write a formatted string to a stream
vprintf[]
Display the output as a formatted string according to format
vsprintf[]
It returns a formatted string
wordwrap[]
Wraps a string to a given number of characters
Hàm strtolower [] trả về chuỗi theo chữ thường.
Hàm strtouper [] trả về chuỗi trong chữ hoa.
Hàm ucfirst [] trả về chuỗi chuyển đổi ký tự đầu tiên thành chữ hoa. Nó không thay đổi trường hợp của các ký tự khác.
Hàm lcfirst [] trả về chuỗi chuyển đổi ký tự đầu tiên thành chữ thường.Nó không thay đổi trường hợp của các ký tự khác.
Hàm ucwords [] trả về chuỗi chuyển đổi ký tự đầu tiên của mỗi từ thành chữ hoa.
Hàm strrev [] trả về chuỗi đảo ngược.
Hàm strlen [] trả về độ dài của chuỗi.