Thread: Can someone please check my code, I'm having a difficult time trying to get pi.

We must use a dartboard method to approximate pi to two decimal places. We must use only the three libraries listed. We must ask a user to feed a seed into the random number generator .
Input: Enter a seed value: 320
Output: PI is approximately 3.14
Input: Enter a seed value: 780
Output: PI is approximately 3.14

Code:

#include <stdio.h> /* standard input and output */
#include <math.h> 
#include <stdlib.h> /* srand() */ 
#define SEED 10000000 /* number of throws at dartboard */
int main (){
    int darts; /* number of darts thrown */
    double x, y, z, pi; /* x and y are the first quadrant points, z is the square of x and y, pi is used approximate pi */
    int p, count=0; /* p stands for number of hits inside the quadrant */
    printf("Enter a seed value: \n"); /* user inputs a seed value */
    scanf("%d", &darts); /* gets seed value from user and feeds it into number darts thrown */
    srand(SEED); /* random number generator */
    count=0; /* sets initial counting to 0 */
    for (p=0; p<darts; p++){ 
        x=(double)rand()/RAND_MAX;
        y=(double)rand()/RAND_MAX;
        z=((x*x)+(y*y)); /* square of distance to origin */
        if (z<=1) count++;}
        pi=(double)count/darts*4;
        printf("PI is approximately %f \n", pi);
        return 0;
    }

so i should feed the random number generator with just seed?

thank you! but I'm still not getting the output value of 3.14, i get like 3.15 if seed value is 450 and 3.18 if seed value is 890

Code:

#include <stdio.h> /* standard input and output */
#include <math.h> 
#include <stdlib.h> /* srand() */ 
#define SEED 10000000 /* number of throws at dartboard */
int main (){
    int darts; /* number of darts thrown */
    double x, y, z, pi; /* x and y are the first quadrant points, z is the square of x and y, pi is used approximate pi */
    int p, count=0; /* p stands for number of hits inside the quadrant */
    printf("Enter a seed value: \n"); /* user inputs a seed value */
    scanf("%d", &darts); /* gets seed value from user and feeds it into number darts thrown */
    srand(darts); /* random number generator */
    count=0; /* sets initial counting to 0 */
    for (p=0; p<SEED; p++){ 
        x=rand(), y=rand();
        if (x<0) x=-x;
        if(y<0) y=-y;
        z=((x*x)+(y*y)); /* square of distance to origin */
        }
        if (z<=1) count++;{
        pi=(double)count/darts*4;
        printf("PI is approximately %.2f \n", pi);
        return 0;
    }
}

This is what i have but the output is now: PI is approximately 0.00.
How would i get the output to be PI is approximately 3.14 for any seed value?

I've been meaning to tell you, but the indentation in your program is so bad that it is hiding problems. This is your program when it's legibly indented:

Code:

#include <stdio.h> /* standard input and output */
#include <math.h> 
#include <stdlib.h> /* srand() */ 
#define SEED 10000000 /* number of throws at dartboard */
int main ()
{
    int darts; /* number of darts thrown */
    double x, y, z, pi; /* x and y are the first quadrant points, z is the square of x and y, pi is used approximate pi */
    int p, count=0; /* p stands for number of hits inside the quadrant */
    
    printf("Enter a seed value: \n"); /* user inputs a seed value */
    scanf("%d", &darts); /* gets seed value from user and feeds it into number darts thrown */
    srand(darts); /* random number generator */
    
    count = 0; /* sets initial counting to 0 */
    for (p=0; p<SEED; p++)
    { 
        x = rand(), y = rand();
        if (x < 0) x = -x;
        if (y < 0) y = -y;
        z=((x*x)+(y*y)); /* square of distance to origin */
    }
    if (z <= 1) 
        count++;
    
        
    {
        pi = (double)count / darts * 4;
        printf("PI is approximately %.2f \n", pi);
        return 0;
    }
}

Now the question is, is this how you intended the program to work? I don't think z is ever less than or equal to 1, so 0/darts * 4 is 0.

sorry about the indentation, still a newbie here

i was trying to set count as the number of hits. where pi is approximately equal to 4x/n and n is the darts