rand() in c

[coreofreeality]

hi

i was trying to write a simple guess the number game in c using a pseudoRNG for the number the user has to guess.

i've tried to google it, and to look in several places, but they either dont have it, or dump a code and dont really explain how to use it. i've gotten as far as using a value from the system clock to seed srand() and then use rand() to produce an actual random number, but i have no idea how to implement it to store it in a simple integer (lets say int r for the moment)

does anyone know?

[LaRoza]

i was trying to write a simple guess the number game in c using a pseudoRNG for the number the user has to guess.

does anyone know?



#include <stdio.h>
#include <stdlib.h>

int main()
{
int r;
char guess[4];
int guessCount = 0;
srand((unsigned)time(NULL));
r = rand()%100;
do
{
fgets(guess,3,stdin);
if (atoi(guess) == r)
{
printf("You got it in %d tries\n",guessCount);
}
else
{
guessCount++;
if (atoi(guess) > r)
{
puts("Too high");
}
else
{
puts("Too low");
}
}
} while (atoi(guess) != r);
}

[kavon89]

I found this website (http://eternallyconfuzzled.com/arts/jsw_art_rand.aspx) to have lots of info and a basic example of rand() and how to implement it so it produces better random numbers.

[coreofreeality]

thanks! thats much simpler then the code i found on the internets (they used all kinds of other stuff)

[LaRoza]

thanks! thats much simpler then the code i found on the internets (they used all kinds of other stuff)

I updated my code. The game is silly, as it is easy to play. (Think, binary search)

[coreofreeality]

yeah, i was just using it as a little excersise to remember things i learned last semester.

i added things like restricting it to 5 guesses (makes it abit harder) and adding an option from within to play again (instead of having to restart the program.)

[coreofreeality]

by the looks of it, this is an incredibly bloated way of doing what i did,does anyone have advice on how to do it better?


#include <stdio.h>
#include <stdlib.h>
#include <string.h>


//prototype declarations
int guess(int random);
void winresponse(int win, int r);
void ask();

int main()
{
int win, loop=1, r;
printf("wecome to 'guess the number'\n\n");
printf("you have 5 guesses to guess a randomly generated\n");
printf("between 1 and 100. see if you can guess it before\nyour guesses run out!\n\n");
while(loop==1)
{
srand((unsigned)time(NULL));
r = rand()%100; //gives r a pseudorandom number
win=guess(r); //main function controlling guesses
winresponse(win,r); //gives a response based on the result
ask(); //kills program if user return no, only continues if use returns yes.
continue;
}
}

int guess(int random)
{
int i=1, guess, pwn=0;
while(i<6) //you have 5 guesses
{
printf("guess number %d.\n",i);
printf("your guess is: ");
scanf("%d",&guess);
if(guess<random)
{
printf("\n\nhigher\n\n"); //output if guess is too low
}
if(guess>random)
{
printf("\n\nlower\n\n"); //output if guess is too high
}
if(guess==random)
{
printf("\n\n"); //if guess is right, this sets it up for the win message
pwn=1;
i=12;
}
i++;
}
return pwn;
}

void winresponse(int win, int r) //win messages...yay
{
if(win==1)
{
printf("Well Done!!! you won!!\n\n");
}
else
{
printf("too bad. better luck next time\nthe answer was %d\n\n",r);
}
}

void ask() //function to take care of repeated plays, or to exit
{
char grilled[5];
int f=1;
while(f==1)
{
printf("Do you want to play again? ");
scanf("%s",&grilled);
if(strcmp(grilled,"no")==0)
{ //user returns no and program exits
printf("\n\n\n\n");
exit(1);
}
if(strcmp(grilled,"yes")==0)
{
f=2 //user returns yes and plays again
}
else
{
printf("please answer 'yes' or 'no'\n"); //user does not answer yes or no, so program prompts again
}
continue;
}
}

[Tony Flury]

A trivial thing - but there is no reason to use "continue" in your While loop in the ask function - it is at the end of the loop anyway.

A good compiler will probably optimise it out anyway - but I would suggest that it ia bad habit to get into (almost as bad as things like goto).

[Cygnus]

As I recall it just using modulo (%) on the number from rand() is not so good (the low order bits of random numbers repeats more regularly than the whole number). Try this instead:



int randint(int min,int max)
{
return min+int((max-min+1)*(rand()/(RAND_MAX+1.0)));
}