Thread: Searching array of structs within interval

Hello.

I'm having a difficult time trying to solve a problem I have.
This program randomises radius and x-coordinate for balls in an array of structs. What I want to do is find balls within an intervall specified by user input.

For example, lets say the user only wants to see balls that have radius between 1 and 4, the program should then only show all the balls that have the radius 1,2,3,4.

Can someone please nudge me in the right direction on how to solve this? Thank you.

My code so far:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define NBALL 100

typedef struct{
    float radius;
    float x;
}Ball;


int addBalls(Ball ABALL[], int *nrofballs);
void viewBalls(Ball ABALL[], int *nrofballs);
void findBalls(Ball ABALL[], int *nrofballs);


int main(void){

srand(time(NULL));
char mainmenu;
Ball ABALL[NBALL]={0};
int *nrofballs, i;
nrofballs=&i;


    do{
        printf("vaf");
        scanf(" %c", &mainmenu);
        switch(mainmenu){
            case 'q': printf("Program exit success."); break;
            case 'v': viewBalls(ABALL, &i); break;
            case 'a': addBalls(ABALL, &i); break;
            case 'f': findBalls(ABALL, &i); break;
            default : printf("Error.\n"); break;
            }
        }while (mainmenu!='q');


    return 0;
}

void viewBalls(Ball ABALL[], int *nrofballs){


    for(int i=0; i < *nrofballs; i++){
        printf("\n%d\t", i);
        printf("Radius: %f\t", ABALL[i].radius);
        printf("X: %f\n", ABALL[i].x);
    }
}


int addBalls(Ball ABALL[], int *nrofballs){
int i;
i=*nrofballs;

    printf("How many: ");
    scanf("%d", nrofballs);

    for (i=0; i < *nrofballs ; i++){
        ABALL[i].radius = rand() %9+1;
    }
    for (i=0; i < *nrofballs; i++){
        ABALL[i].x = rand() %100+0;

    }
    *nrofballs=i;
    return *nrofballs;
}

void findBalls(Ball ABALL[], int *nrofballs){
float max, min;
int i, j, swap;

    printf("Set min and max values of the radius: ");
    scanf("%f %f", &min, &max);

/* Sort balls first */
        for (i=0; i < (*nrofballs-1); i++){
        for (j=0; j < *nrofballs-i-1; j++){
        if (ABALL[j].radius > ABALL[j+1].radius){
        swap = ABALL[j].radius;
        ABALL[j].radius = ABALL[j+1].radius;
        ABALL[j+1].radius = swap;
      }
    }
  }
}

Thanks for the reply. Just started with C, so I appreciate all the tips!

I added this to my function:

Code:

void findBalls(Ball ABALL[], int *nrofballs){
float max, min;
int i;
        printf("Set min and max values of the radius: ");
        scanf("%f %f", &min, &max);

        for(int i=0; i < *nrofballs; i++){
        if (ABALL[i].radius == min && ABALL[i].radius == max){
        printf("\n%d\t", i);
        printf("Radius: %f\t", ABALL[i].radius);
        printf("X: %f\n", ABALL[i].x);
        }
    }
}

But it seems when using && the compiler just ignores the whole for loop. Why is that? Do i need to make two for loop for the linear search to work for two values?

Thank you.

Oh, did not know that at all. Now it's working. Thank you very much.
Instead of starting another topic I will ask in this thread.

My function for adding balls seems to overwrite all the other elements in the array. Code is as follows

Code:

int addBalls(Ball ABALL[], int *nrofballs){int i;
i=*nrofballs;


    printf("How many: ");
    scanf("%d", nrofballs);

    for (i=0; i < *nrofballs ; i++){
        ABALL[i].radius = rand() %9+1;
    }
    for (i=0; i < *nrofballs; i++){
        ABALL[i].x = rand() %100+0;
    }
    *nrofballs=i;
    return *nrofballs;
}

Is it not possible to make the scanf add balls after last known position? Should it not just be to make the pointer 'go' to the next element - like - (*nrofballs)++?