PHP cannot find the class?

{Code...} Why is an error reported? Fatalerror: Class & #039; testString & #039; notfound. If I remove extendsFather, the output will be normal.

    
  test1());    class testString extends Father{        public function test1(){            return 1;        }    }

Why is an error reported?

Fatal error: Class 'testString' not found

If I removeextends FatherThen the output is normal.

Reply content:

    
   test1());    class testString extends Father{        public function test1(){            return 1;        }    }

Why is an error reported?

Fatal error: Class 'testString' not found

If I removeextends FatherThen the output is normal.

First, from the code you posted, you should write it in two files. There is no require or include Father class file in the testString class file.
Second, it is also the key to your problem. The sequence of class declaration. During file compilation, when the testString class declaration is compiled, no Father class is found (that is, not declared ), in this case, the testString class Declaration fails. You can use class_exists () to verify it. Therefore, when the testString class is instantiated, the error "class 'teststring' not found" is returned.

Declare the parent class before it inherits its subclass.

Because your definition is behind the call.

Definitely wrong.

Sequential execution,testStringYou have not defined it.new.

Write the parent class before the subclass. instantiate the class after it is defined.