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    addcslashes

    (PHP 4, PHP 5, PHP 7, PHP 8)

    addcslashes — Quote string with slashes in a C style

    Description

    addcslashes(string $string, string $characters): string

    Returns a string with backslashes before characters that are listed in characters parameter.

    Parameters

    string

    The string to be escaped.

    characters

    A list of characters to be escaped. If characters contains characters \n, \r etc., they are converted in C-like style, while other non-alphanumeric characters with ASCII codes lower than 32 and higher than 126 converted to octal representation.

    When you define a sequence of characters in the characters argument make sure that you know what characters come between the characters that you set as the start and end of the range.

    <?php
    echo addcslashes('foo[ ]', 'A..z');
    // output: \f\o\o\[ \]
    // All upper and lower-case letters will be escaped
    // ... but so will the [\]^_`
    ?>
    Also, if the first character in a range has a higher ASCII value than the second character in the range, no range will be constructed. Only the start, end and period characters will be escaped. Use the ord() function to find the ASCII value for a character.
    <?php
    echo addcslashes("zoo['.']", 'z..A');
    // output: \zoo['\.']
    ?>

    Be careful if you choose to escape characters 0, a, b, f, n, r, t and v. They will be converted to \0, \a, \b, \f, \n, \r, \t and \v, all of which are predefined escape sequences in C. Many of these sequences are also defined in other C-derived languages, including PHP, meaning that you may not get the desired result if you use the output of addcslashes() to generate code in those languages with these characters defined in characters.

    Return Values

    Returns the escaped string.

    Examples

    characters like "\0..\37", which would escape all characters with ASCII code between 0 and 31.

    Example #1 addcslashes() example

    <?php
    $escaped     = addcslashes($not_escaped, "\0..\37!@\177..\377");
    ?>

    See Also

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    User Contributed Notes 3 notes

    up
    7
    phpcoder at cyberpimp dot pimpdomain dot com
    19 years ago
    If you are using addcslashes() to encode text which is to later be decoded back to it's original form, you MUST specify the backslash (\) character in charlist!

    Example:

    <?php
    $originaltext     = 'This text does NOT contain \\n a new-line!';
    $encoded = addcslashes($originaltext, '\\');
    $decoded = stripcslashes($encoded);
    //$decoded now contains a copy of $originaltext with perfect integrity
    echo $decoded; //Display the sentence with it's literal \n intact
    ?>

    If the '\\' was not specified in addcslashes(), any literal \n (or other C-style special character) sequences in $originaltext would pass through un-encoded, but then be decoded into control characters by stripcslashes() and the data would lose it's integrity through the encode-decode transaction.
    up
    3
    stein at visibone dot com
    17 years ago
    addcslashes() treats NUL as a string terminator:

    assert("any" === addcslashes("any\0body", "-"));

    unless you order it backslashified:

    assert("any\\000body" === addcslashes("any\0body", "\0"));

    (Uncertain whether this should be declared a bug or simply that addcslashes() is not binary-safe, whatever that means.)
    up
    1
    natNOSPAM at noworrie dot NO_SPAM dot com
    22 years ago
    I have found the following to be much more appropriate code example:

    <?php
    $escaped     = addcslashes($not_escaped, "\0..\37!@\@\177..\377");
    ?>

    This will protect original, innocent backslashes from stripcslashes.
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