procedural

I am learning PHP, and from the example I have seen on the internet there is a mixture in the coding of programs, from object ... this really common or am I wrong? If PHP is an object-oriented language, to what extent is this mixture interesting or not?

I would like to know what are the characteristics that define the paradigm of structured programming, and what is the differe ... ; } void subtrai() { printf("\n\nSubtracao: %d", valor1 - valor2); } Note: Can cite examples in the C language.