Since you’re allocating a char array but do not initialize it, strlen() will count from the beginning of the tab pointer to the first NUL character. So the result depends on the contents of your program’s heap. 3 solved Strlen returns undefined behaviour with C++ [duplicate]
strlen(myarray) returns the index of the first 00 in myarray. 0 solved strlen() gives wrong size cause of null bytes in array
This is what those functions do exactly: substr() is used to generate a sub-string of specified length from another string. strlen() will return the length of the provided string. Code substr($query,0,strlen($query)-2) removes comma and space from foreach Loop. solved What is the purpose of strlen($query)-2;