Detailed explanation of common functions in PHP

Commonly used PHP functions:

String processing function:

Powerful features:

1. Other types of data used in string processing functions will automatically convert them into strings before processing

2. You can use the string as an array, as a collection of characters, as: $ Str = "Lijian"; Echo $ Str [1]; but this will make people mistakenly think that it is an array, so it usually writes: echo $str{1};

                                                                                                                                                                      takes out the first two characters: echo $str[0].$str[1]; A new format string

Trim (); default is deleting space. Note that the deletion here is not the real deletion

trim ($ str, '0..9.'); There are still spaces

            ltrim($str,'1'); delete the number 1 on the left

          rtrim($str,'0..9'); . l2br；

htmllentities( ;                                                                                                                                  using Function:

                                                    use       using natural ordering algorithm

    using strnatcmp()

                                                                                                                                                                                                            strstr(): Distinguish the size Write, return the string starting from the matching place

          stristr(): case-insensitive

            stripos(): Find the position where the string first appears, case-insensitive

        strpos(): Find the string The first occurrence position, case-sensitive

strrpos(): Find the last occurrence position of the string, case-sensitive strripos(): Find the last occurrence position of the string, case-insensitive

substr(): Also If there are other string 子 if you put the numbers in the number, you can automatically convert it into a string, such as: Substr (123456,2,4);

Str_replace (String, String, String): L Str_replace (Array, String, String): Replace multiple of multiple with one

Str_replace (Array, Array, String): Replace multiple

str_ireplace (): Do not distinguish between manuscripts ():::) Convert a string into an array

Implode(): Convert an array into a string

Array function:

What is the difference between array_map();

mysqli_fetch_assoc() and mysqli_fetch_row() and mysqli_fetch_object()?

Using mysqli_fetch_assoc() and mysqli_fetch_row() both return the query results into an array, both return the first row and then move the pointer down one row.

Difference: mysqli_fetch_assoc() uses keyword index to obtain the value. For example:

$row = $result->fetch_assoc();

echo $row['username'];

But mysqli_fetch_row() uses a numeric index to obtain the value. For example:

$row = $result->fetch_row();

echo $row[0];//Note: "0" means the first field in the table (that is, username is the first field in the table) a field).

There is also another function: mysqli_fetch_object() to get a row back into an object, and then get the value through a class, for example:

$row = $result->fetch_object();

echo $row- >username;

The above has introduced a detailed explanation of commonly used functions in PHP, including relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.