The end of the cycle: break out of the entire loop, the remaining loop body, do not need to be executed. continue: jumps out of the current loop, ending only the current loop body, while the rest of the loop body continues to execute. Our Process Control statements can be nested. There may be loops within the loop inside the branch branch within the loop loop. When there is a loop inside the loop, we call it multiple loops! For example Delete a multiplication table: If you write a break or continue within a multiple loop, control the loop that contains the break or continue directly. If we need to simultaneously end Multiple loops  , you should add parameters after break or continue to indicate the number of loops that jump out (end). The parameter is an integral type 1 represents a layer default. 2 represents 2 floors. Analogy Continue can also be used in the same way as above. There are also exceptions: when a loop statement inner set branch (switch) occurs, terminates if needed: is swtich as the loop because of PHP internal . The file contains a php file containing another PHP file. Include Require where filename section can be a relative address can also be an absolute address for . Relative Address: The file that needs to be loaded, relative to an address of the current file. Absolute Address: On Windows start with the letter to reach the real address of a file. If Linux is under with / start with For example loading files: Usually in a PHP project, the use of absolute address is relatively large. above include and require functions exactly the same, so the use of methods and effects are no different. Because there is a different level of requirements for the target loading file: Causes a different error level if the target file is incorrect. Include require include_once require_once have once loading that will be   before the load is executed, and the target script should be judged firstWhether it has been, loaded into the current script. If it is already loaded, it will not be loaded again. Different from the loading without once. The difference between include_once and required_once: The difference is the same as include and require: Return is used in functions Using return outside of a function is equivalent to stopping script execution. But when return writes to loaded script, the behavior changes in the if it is written to the target file, then return means: Target file 36.php Loading his file: We receive the return value of the include; We usually use this feature the configuration file for the project: Profile: Use configuration: Job for ( $i =0 ; $i <=10; $i ++) { switch ($i) { case 3: echo ' Swtich '; break 2;//continue 2; echo $i; If the code is as above, if break is replaced by continue , try to explain why.