# Lec13 - Lecture 13 Random Numbers PIC 10A Todd Wittman Sec...

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1 Lecture 13: Random Numbers PIC 10A Todd Wittman Sec 3.11 : Random Numbers ring2 The rand() function creates a random integer between 0 and RAND_MAX, a constant about 32,000. ring2 To generate a random integer in the range [a,b] use a + rand()%(b-a+1); ring2 Ex Simulate the roll of a die. ring2 Ex Generate a random even integer between 2 and 10.

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2 int i = 1; while (i <= 20) { int rand_num = rand(); cout << rand_num << "\n"; i++; } Gives the same output every time we run it! 4 runs of the program Seeding Your Randomness ring2 The problem is that the rand() function doesn’t really generate a random number. ring2 It just reads a number from a really long built-in list of integers. ring2 So it always reads the same list every time we restart the program. ring2 To make it look more random, we should start reading the list from a different spot. ring2 This is called seeding the random number generator.
3 Seeding Your Randomness ring2 The srand(int) function starts reading the list at the seed position specified by the passed int.

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