Curso de Programação C | Como gerar números aleatórios com as funções rand e srand? | aula 103

Coupons for my Udemy courses https://wagnergaspar.com/cupons_udemy/ Welcome to lesson number 103 of our free programming course in the C language. Typing numbers on the keyboard to test our programs can be quite laborious, especially with larger vectors. A very useful function is the rand() function, which we will learn about in this lesson. This function is used to generate random values. So, when we loop to fill a vector by reading values ​​from the keyboard, we can simply generate values ​​to fill our vector, like this: for(i = 0; i less than tam; i++) vet[i] = rand(); However, when running the program a few times, you will notice that the same values ​​are always generated. Why does this happen? The truth is that it's not possible to generate completely random numbers, to generate numbers "out of thin air". We need to start from something, from some initial value. Whoever wrote this function defined some initial value that is used to generate the numbers. The same values ​​are always generated because a default value called a seed is always used. To generate a different sequence in each execution, we need to specify our seed, a value that is different in each execution of our program. A very useful value as a seed is the computer's time, which will be different in each execution of the program, even if only by milliseconds. To use the computer's time as a seed, simply use the `srand()` function once, as follows: `#include time.h` `srand(time(null));` The `srand()` function changes the default seed to the new seed received as a parameter between the parentheses. To obtain the current computer time, we need the `time.h` library. This library contains the function that will return the computer's time: `time(null)`. Code available at: https://wagnergaspar.com/