PHP function

The difference between the array_merge function and the addition of two arrays

　The array_merge function, when the same index array appears, will merge the index arrays in the two arrays, and add them up with the maximum index value of the first array. If it is an associative array, the value of the subsequent array will overwrite the previous one. Value, for addition, regardless of the index or associative array that appears first, the former is used as the value, and the latter is discarded

array_chunk function

　 To cut the array, the first parameter is the array to be cut, the second parameter is the number of elements in each array after cutting, and the third parameter is whether the index of each divided array uses the index name of the original array. , the default is not used

next function

　Returns the value of the next element of the current array element, moves the pointer backward one position, returns false if it does not exist

prev function

　Returns the previous element of the current element and moves the pointer forward one position. Returns true if it does not exist

end function

　Return the value of the last element of the array

current function

　Return the current element of the array without moving the position

sort function

　 Sort the values ​​of the array elements in forward order, return true if successful, false if failed. The first parameter is the array to be sorted, and the second parameter is the sorting rule. This function will delete all the original elements of the sorted array. Index value, add new index value after sorting

rsort function

　 Sort the values ​​of the array elements in reverse order, returning true if successful and false if failed. The first parameter is the array to be sorted, and the second parameter is the sorting rule. This function will delete all original indexes of the sorted array. value, add new index value after sorting

asort function

　 Sort the values ​​of the array elements in forward order and save the index relationship. Return true if successful, false if failed. The first parameter is the array to be sorted, and the second parameter is the sorting rule. The function will maintain the original There is a corresponding relationship between key and value

ksort function

　 Sort the keys of the array elements in forward order, return true if successful, false if failed. The first parameter is the array to be sorted, and the second parameter is the sorting rule. This function will maintain the original key-value correspondence. Relationship

shuffle function

Randomly sort the array elements, delete the original key-value relationship, return true if successful, false if unsuccessful

array_reverse function

Sort the array elements in the reverse direction of the original order. The second parameter is the sorted array. If the second parameter is set to true, the original relationship will be maintained after sorting. The default is false

reset function

　Reset an array and move the internal pointer in the array to the cell where the first element of the array is located. If the data is empty, return false

list function

　Assign the elements of the array to variables, and the array is an index array

range function

　Quickly create an array within a specified range. The first parameter is the start value, the second parameter is the end value, and the third parameter is the span. The default is one

array_push function

　 Push one or more elements into the end of the array. Successful execution returns the number of units pushed into the array

array_pop function

　Pop the last element of the array, return the last unit of the array, and reduce the length of the array by one. If the array is empty or not an array, return null. After use, the array pointer will point to the first array unit

array_change_key_case function

　Replace all case of strings as array indexes, the first parameter is the array, and the second parameter specifies whether to use uppercase or lowercase

array_intersect function

To calculate the intersection of arrays, there can be multiple parameters, and the key-value correspondence remains unchanged

array_flip function

　Exchange index and value

array_fill function

Set some or all elements in the array to a value. The first parameter is the starting index of the element to be filled, the second parameter is the number of filling, and the third parameter is the value of the filled element

count function

　Count the number of elements in the array

array_count_values ​​function

　Count the number of times each value occurs in the array

array_key_exists function

　Check whether the given index exists in the array, return true if it exists, otherwise return false

array_keys function

　 Get all the index names in the array. The first parameter is the array itself. The second parameter is the key value to be selected. The default is all. You can specify a key value to search. The third parameter is used to perform congruence. Compare

array_map function

Apply the callback function to the given array

in_array function

Determine whether a certain value exists in the array. If it exists, it returns true, if not, it returns false. The first parameter is the value you want to find, the second parameter is the array, and the third parameter is used for congruent comparison

key function

　Get the key name of the element pointed to by the current pointer from the associative array

strcmp function

Compare two strings, if str1 waits for str2, return 0, if str1 is less than str2, return -1, if str1 is greater than str2, return a number greater than 0

str_replace function

　Replace all the $search part in str in the string with the string $replace, and return the replaced string. The first parameter is the data to be replaced, the second parameter is the value to be replaced, and the third parameter is the value to be replaced. The first parameter is the string to be operated on, the fourth parameter is the number of substitutions, and when the first and second parameters are arrays, a corresponding relationship is formed

substr_replace function

　The first parameter is the string to be processed, the second parameter is the string to be replaced, and the third parameter is the starting position of the string to replace. If start is a positive number, the replacement will be from the start position of the string. start. ,If start is a negative number, the replacement will start from the penultimate start position of string. The third parameter is the replacement length. If this parameter is set and is a positive number, it indicates the length of the replaced substring in string. If set to a negative number, it represents the number of characters from the end of string to the end of the substring to be replaced. If this parameter is not provided, it defaults to strlen( string ) (the length of the string). Of course, if length is 0, then the function of this function is to insert replacement into the start position of string.

sprintf function

　Format a string. The first parameter is the format to be converted, usually starting with % and ending with the characters being converted. The second parameter is the data to be formatted

substr function

　Get a substring in a string. The first parameter is the string to be processed, the second parameter is the starting position, and the third parameter is the length to be intercepted

rtrim function

　Delete the blank characters (or other specified characters) at the end of the string. The first parameter is the string to be processed, and the second parameter is the character you specify. If not specified, it will be the default

ltrim function

　Delete the blank characters (or other specified characters) at the beginning of the string. The first parameter is the string to be processed, and the second parameter is the character you specify. If not specified, it will be the default

trim function

　Remove whitespace characters (or other specified characters) at the beginning and end of the string

strlen function

　Get the length of a string

mb_strlen function

　Get the length of a string, the first parameter is the string to get the length, the second parameter is the character set to be specified

strtoupper function

Convert all letters in the string to uppercase letters

strtolower function

Convert all letters in the string to lowercase letters

str_repeat function

Used to repeatedly generate a string, the first parameter is the string to be repeatedly generated, and the second parameter is the number of times to be repeated

str_split function

　 Split the string into an array. The first parameter is the string to be processed, and the second parameter is the length of the cutting

file_put_contents function

　The first parameter is the path to the file to be written, the second parameter is the content to be written, it will be automatically created if the file to be written does not exist, and the default is replacement writing. When the third parameter is FILE_APPEND, it is expressed as Append writing, the return value is the number of bytes written.

file_get_contents function

Get the file content of the specified path. It is not suitable to be used when the file read is too large. The return value is the obtained content

fopen function

　The first parameter is the path of the file to be opened, and the second parameter is the method of opening the file: r, w (the file will be automatically created if it does not exist, and the file content will be cleared), a, x (the file will not be automatically opened if it does not exist). Create, the file content will be cleared), r+, w+, a+, x+, the return value is the file resource

fwrite function

　The first parameter is the open file resource, the second parameter is the string content of the read length, the size is bytes, the maximum is 8192 bytes

fgets

　The first parameter is the file resource, and the second parameter is to read a string of specified length,