c - 是否有某种方法可以对结构进行排序，同时仅使用指针将其传递到 void 函数中？

Question

我试图通过使用指针在排序函数中的 XY 坐标系上对一些随机点以及这些点与用户输入点的距离(将其视为 (0,0)，即原点)进行排序，当我从排序函数中删除点排序代码时，距离排序就可以了，但是当我尝试对点以及距离进行排序时，代码不起作用。我知道有人问过有关排序点的类似问题，但我知道我想仅使用指针来实现它的逻辑。有人可以帮忙吗？

代码

#include <stdio.h>
#include <math.h>

struct point {
    float x, y;
};

void sort();

int main() {
    int n;
    printf("Enter the number of points in the system:");
    scanf("%d", &n);
    float d[n], xi, yi;
    struct point p[n];
    printf("\nEnter the X and Y coordinates of the points-\n");
    
    for (int i = 0; i < n; i++) {
        printf("Enter the X coordinate of point %d: ", i + 1);
        scanf("%f", &p[i].x);
        printf("Enter the Y coordinate of point %d: ", i + 1);
        scanf("%f", &p[i].y);
    }
    
    printf("\nPoints entered are-\n");
    
    for (int i = 0; i < n; i++) {
        printf("%d- (%0.2f,%0.2f)\n", i + 1, p[i].x, p[i].y);
    }
    
    printf("\nEnter the X coordinate of point from which distance is to be calculated:");
    scanf("%f", &xi);
    printf("Enter the Y coordinate of point from which distance is to be calculated:");
    scanf("%f", &yi);
    
    for (int i = 0; i < n; i++) {
        d[i] = fabs(sqrt(pow(((p[i].x) - xi), 2) + pow(((p[i].y) - yi), 2)));
    }
    
    printf("\nDistance- ");
    
    for (int i = 0; i < n; i++) {
        printf("%0.2f  ", d[i]);
    }
    
    printf("\n");
    sort(d);
    printf("\n\nSorted distance- ");
    
    for (int i = 0; i < n; i++) {
        printf("%0.2f  ", d[i]);
    }
    
    printf("\n\n");
    
    for (int i = 0; i < n; i++) {
        printf("%d- (%0.2f,%0.2f)\n", i + 1, p[i].x, p[i].y);
    }
}

void sort(float *d, struct point *p) {
    for (int i = 0; i < sizeof(d) / sizeof(float); i++) {
        for (int j = 1; j < (sizeof(d) / sizeof(float)) - i; j++) {
            if (*(d + i) > *(d + i + j)) {
                float temp = *(d + i), pxtemp = (p + i)->x, pytemp = (p + i)->y;            
                *(d + i) = *(d + i + j);                                              
                *(d + i + j) = temp;
                /*(p + i)->x = (p + i + j)->x;
                (p + i + j)->x = pxtemp;
                (p + i)->y = (p + i + j)->y;
                (p + i + j)->y = pytemp;*/
            }
        }
    }
}

输出

Enter the number of points in the system:2

Enter the X and Y coordinates of the points-
Enter the X coordinate of point 1: 5
Enter the Y coordinate of point 1: 6
Enter the X coordinate of point 2: 3
Enter the Y coordinate of point 2: 4

Points entered are-
1- (5.00,6.00)
2- (3.00,4.00)

Enter the X coordinate of point from which distance is to be calculated:0
Enter the Y coordinate of point from which distance is to be calculated:0

Distance- 7.81  5.00

Answer 1

代码中存在多个问题:

• 您没有将 p 传递给 sort 函数。
• 在此 sort 函数中，sizeof(d)/sizeof(float) 不会计算出 d< 指向的数组中的条目数 因为 d 只是一个指针。您必须将数组 n 的长度作为额外参数传递。

#include <math.h>
#include <stdio.h>

struct point {
    float x, y;
};

void sort(float *d, struct point *p, int n) {
    for (int i = 1; i < n; i++) {
        for (int j = 0; j < n - i; j++) {
            if (d[i] > d[i + 1]) {
                float temp = d[i];
                d[i] = d[i + 1];
                d[i + 1] = temp;
                struct point temp1 = p[i];
                p[i] = p[i + 1];
                p[i + 1] = temp1;
            }
        }
    }
}

int main() {
    int n;
    printf("Enter the number of points in the system:");
    if (scanf("%d", &n) != 1 || n < 1)
        return 1;
    float d[n], xi, yi;
    struct point p[n];
    printf("\nEnter the X and Y coordinates of the points-\n");
    
    for (int i = 0; i < n; i++) {
        printf("Enter the X coordinate of point %d: ", i + 1);
        if (scanf("%f", &p[i].x) != 1)
            return 1;
        printf("Enter the Y coordinate of point %d: ", i + 1);
        if (scanf("%f", &p[i].y) != 1)
            return 1;
    }
    
    printf("\nPoints entered are-\n");
    
    for (int i = 0; i < n; i++) {
        printf("%d- (%0.2f,%0.2f)\n", i + 1, p[i].x, p[i].y);
    }
    
    printf("\nEnter the X coordinate of point from which distance is to be calculated:");
    if (scanf("%f", &xi) != 1)
        return 1;
    printf("Enter the Y coordinate of point from which distance is to be calculated:");
    if (scanf("%f", &yi) != 1)
        return 1;
    
    for (int i = 0; i < n; i++) {
        // use hypot() to compute the distance between 2 points
        // it has better behavior than sqrt(dx2 + dy2) in corner cases.
        d[i] = hypot(p[i].x - xi, p[i].y - yi);
    }
    printf("\n");

    printf("Distance- ");
    for (int i = 0; i < n; i++) {
        printf("%0.2f  ", d[i]);
    }
    printf("\n");

    sort(d, p, n);

    printf("\n\nSorted distance- ");
    for (int i = 0; i < n; i++) {
        printf("%0.2f  ", d[i]);
    }
    printf("\n\n");
    
    for (int i = 0; i < n; i++) {
        printf("%d- (%0.2f,%0.2f)\n", i + 1, p[i].x, p[i].y);
    }
    return 0;
}