Ch.9b String Manipulation

8/9/2019 Ch.9b String Manipulation

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String Manipulation

By Tony Chun Kuen WONG

Working with String

Formatting string

Joining and Splitting strings

Matching and replacing substrings withstring functions


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trim( ); Strips whitespace from the start and end of a

s r ng, an re urns e resu ng s r ng. s r ps Newlines (\n), Carriage return (\r) , Horizontal tab (\t)

, ,

ltrim ( );

start (or left)

cho ; same as above but remove whitespaces from the

end (or right)

Formatting Strings for Presentation

nl2br ( ) function

It takes a string as parameter and replacesall the newlines in it with the HTML
tag


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Formatting Strings for Printing

printf ( ); Prints a formatted string to the browser

sprintf ( );

Returns a formatted string

String Case Functions

e.g. Define String variable $subject = Feedback from web site;

strtoupper($subject); FEEDBACK FROM WEB SITE

ucfirst($subject); Feedback from web site

ucwords($subject); Feedback From Web Site

http://isem03.hkbu.edu.hk/~isemuser20/string/generic_form.html


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Formatting Strings for Storage

AddSlashes ( ); Used to add \ (blakslash) in order to make

the MySQL database can understand theliteral special character like ( ; ; \ ,)

StripSlashes ( );

Opposite to the above function

Joining and Splitting Strings

explode ( );

s unc on a e a s r ng npu an sp s into pieces on a specified separatorstring. Theieces are returned in an arra

implode ( ); join ( ); Reverse the effect of ex lode

strtok ( ); Like ex lode but Token a strin once a time.

substr ( ); Access a substrin between iven start and

end points of a string


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ompar ng r ngs

strcmp ;

The function will compare two string. If they are equal, it.

in lexicographic order, it will return a number greaterthan 0. Otherwise, it will return a number less than 0.This function is case sensitive.

strcasecmp ( ); Same as strcmp ( ) ; not case sensitive

The below two compare string in natural ordering e.g. 2 is less than 12 in the following two

strnatcmp ( ); strnatcasecmp ( );

est ng tr ng engt

strlen ( );

Matching and Replacing Substrings

strstr strchr Use to find a string/character inside a string

If exact match is found, the function returns fromt e rst occurrence, ot erw se t return a se;

stristr ( );

Same as above but not case sensitive

strrchr ( ); It will return from the last occurrence onwards.


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Finding the Position of a Substring

Both functions operate in a similar fashion to, ,substring, they return the numerical position

. strpos ( );

Return the first position

strrpos ( );

Return the last position

We can specify the offset before searching

Replacing Substring

str_replace ( );

_ new_needle, string haystack);

This function will replace all thens ances o nee e n ays ac w

new_needle


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ep ac ng u s r ng

substr_replace ( ); string substr_replace(string string, string

, ,

This function will replace part of the stringwith thestr ng rep acement. c parts s rep ace epen supon the values of the startand the optional lengthparameters.

length

0 inserted into the string

os t ve rep ace t e exact num er o c aracters

Negative represents the point at which youd like to,

the end of the string

Regular Expression

Used for examining text and modifying

text. They enable us to search foratterns within a strin extractin

flexibly and precisely. Be warned that,

are also slower than the more basics r ng unc on.


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Matching regular expressions in PHP is

comparsion because you are matching

string

The string Tony matches the regular

regular expressions on, o and so on.

Character Sets and Classes

. character except a new line (\n)

.at matches the strings cat, sat,and mat, among others


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xpress on n t e square rac etsmatches only a single character

[a-z] limit to character[aeiou] limit to vowel

- -

[^a-z] not between a-z

[[:alnum:]] Alphanumeric characters

[[:alpha:]] Alphabetic characters

[[:lower:]] Lowercase letters

[[:upper:]] Uppercase letters[[:digit:]] Decimal digits

:x g : eax ec ma g s

[[:punct:]] Punctuation

[[:space:]] Whitespace characters

[[:print:]] All printable characters

for space


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epet t on

Symbols means the pattern can berepeated zero or more times

+ Symbols means that the pattern can

The symbol should appear directly after thepart of expression that it applied to

[[:alnum:]]+ means at least one

alphanumeric character.

Subexpressions

Searching for at least one of these

s r ngs o owe y exac y one o ose

e.g.*

, ,

very large, and so on.


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Counted Subexpressions

Specify how many times something can be

curly braces { }.

(very){1, 3}

matc es

very, very very and very very very

(very) {2} matches very very

of a String

You can specify whether a particular

su express on s ou appear a estart, the end, or both.

^ start

o ma c es o a e s ar o a s r ng

com$ matches com at the end of the string


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Branching

Matching through a set of choice

. .

(com)|(edu)|(net) match com, edu, or net

h r r

If we want to match one of the special

characters, you must put a slash (\) infront of it.


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Regular Expression commands

ereg_replace Replace regular expressioneregi_replace Replace regular expression caseinsensitiveereg ase nsens t ve regu ar express on matcsplit Split string into array by regular expression

case insensitive

sql_regcase Make regular expression for casensens ve ma c

. .

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Ch.9b String Manipulation