program using the rand () function

Question

I want to make a simple program in which the rand() function generates a random number out of 1,2,3 and the user is asked to predict the number. if the user predicts the number correctly then he wins otherwise he looses. Here's the program-

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

int main()
{
    int game;
    int i;
    int x;

    printf("enter the expected value(0,1,2)");
    scanf("%d\n",&x);
    for(i=0;i<1;i++){
        game=(rand()%2) + 1

        if(x==game){
            printf("you win!");
        }

        else{
            printf("you loose!");
        }
    } return 0;

}

I think that `game=(rand()%2) + 1` needs to be `game=(rand()%3)` because you use 0,1,2 in the first `printf` — Spikatrix, Apr 29 '15 at 09:27

score 1 · Answer 1 · answered Apr 29 '15 at 09:18

1

Remove \n from your scanf()

scanf("%d\n",&x); to

scanf("%d",&x);

and place a semicolon(;) after game=(rand()%2) + 1; it works.

Your for loop is not required here.

answered Apr 29 '15 at 09:18

Raghu Srikanth Reddy

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score 1 · Accepted Answer · edited May 23 '17 at 10:24

Some issues with your code:

Point 1:

    scanf("%d\n",&x);

should be

    scanf("%d",&x);

Point 2:

for(i=0;i<1;i++)

this for loop is practically useless. It only iterates one. either use a longer counter, or get rid of the loop.

Point 3:

It's better to provide a unique seed to your PRNG. You may want to use srand() and time(NULL) in your function to provide that seed.

Point 4:

game=(rand()%2) + 1

should be

game = rand() % 3; // the ; maybe a typo in your case
                ^
                |
          %3 generates either of (0,1,2)

Point 5:

When you use % with rand(), be aware of modulo bias issue.

Note:

The recommended signature of main() is int main(void).
Always initialize your local variables. Good practice.

score 0 · Answer 3 · edited Apr 29 '15 at 09:25

You didn't ask any question but I guess it is "Why my rand() function doesn't work?"

You need to add these lines

#include <time.h>

and the random initialization at the beginning of the main function:

srand(time(NULL));

Which should give:

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

int main()
{
    srand(time(NULL));
    int game;
    int i;
    int x;

    printf("enter the expected value(0,1,2)");
    scanf("%d",&x);
    for(i=0;i<1;i++){
        game=(rand()%2) + 1;

        if(x==game){
            printf("you win!");
        }

        else{
            printf("you loose!");
        }
    } return 0;

}

Edit: there are other problems as Sourav said

program using the rand () function

3 Answers3