Inversion methods: 1. use "explode(' ',$str)" statement to convert string to array; 2. use "array_reverse($arr)" statement to invert the array and return the array in the reverse order of elements; 3. use "implode(' ',$arr)" statement to convert the inverse array to string.
php to invert strings by word
Implementation method：
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First convert the string into an array of elements by word
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Then use array_reverse() to invert the array
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Then convert the inverse array to a string
Implementation code：
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<?php
$str = "Reversing a string by word";
// break the string up into words
$arr = explode(' ',$str );
// reverse the array of words
$arr = array_reverse($arr);
// rebuild the string
$str = implode(' ',$arr);
print $str;
?>
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Output results：
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The explode() function splits a string based on the string separator, i.e. it splits a string into several substrings based on the separator, and then combines these substrings into an array and returns it.
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The array_reverse() function returns an array in the reverse order of its elements.
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The implode() function converts a one-dimensional array into a string
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