The output prompts the undefined variable: Notice: Undefinedvariable: strin.

The output prompts "Notice: Undefinedvariable: strinfunction & nbsp; Call () {& nbsp; for ($ I = 0; $ I & lt; = 10; $ I ++) & nbsp; & nbs output the following error message: Notice: Undefined variable: str in
Function Call (){
For ($ I = 0; $ I <= 10; $ I ++)
{
$ Str. = $ I ."
";
}
Return $ str;
}

Echo Call ();

Output the prompt "Notice: Undefined variable" to share it :";???????}???? Ret... 'data-pics = ''>
------ Solution --------------------
Notice: Undefined variable
Indicates that you have used the value of a variable without a value assignment.

In your $ str. = $ I ."
"; $ Str is not assigned a value when you first enter, so an error is reported.

Function Call (){
$ Str = ''; // This sentence cannot be fewer
For ($ I = 0; $ I <= 10; $ I ++)
{
$ Str. = $ I ."
";
}
Return $ str;
}

Echo Call ();