Algorithm "handle age":
// idade deve sempre ser positiva, por isso vou usar unsigned
unsigned int t1;
printf("Digite sua idade:");
scanf("%d", &t1);
printf("Idade: %d", t1);
Doubt: Even though I enter with a negative value, 2 printf() appears negative. I did not understand the actual use of the modifier unsigned of int ?
When you use the %d modifier you are indicating a value of the signed integer type, in this case negative.
The correct switch for unsigned is %u . Internally, both signal and non-signal ends using the same number of bits.
The difference is that in the case with sign, it uses the most significant bit to indicate the signal used.
If you want to accept only positives you have to filter properly ( if (t1 >= 0) ).
The type unsigned int indicates only that it will be an unsigned number, it does not prohibit entering a negative number. It is possible to store an originally negative number in it where it loses the signal and generates a very different positive number than you expect.