[英]Trouble printing out values from an array in C
給定一組輸入值時,我正在編寫此程序來計算多邊形的面積和周長。 到目前為止,一切工作都已經成功完成,並且我對直到第3階段的輸出都感到滿意,我遇到的問題看似微不足道,但我似乎找不到它。 在第3階段,我嘗試計算最大的多邊形區域,我需要打印出分配給該多邊形的(x,y)坐標。 我有一種確定最大多邊形的方法,該方法可以工作並輸出正確的多邊形,但是當我嘗試從該多邊形讀取(x,y)坐標到另一個數組並打印這些值時,即使返回,我也一無所獲所有編譯都很好。 我主要關心的是將數組中的值打印出來。
這是我需要的輸出:
Stage 3
=======
Largest polygon is 15643
x_val y_val
1.0 2.0
4.0 5.0
7.8 3.5
5.0 0.4
1.0 0.4
這是我收到的輸出:
Stage 3
=======
Largest polygon is 15643
x_val y_val
這是我的書面代碼:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define MAX_POLYS 100
#define MAX_PTS 100
#define END_INPUT 0
#define PI 3.141592653589793
#define PER_ROW 5
double eccentricity(double perimeter, double area) {
double eccen;
eccen = (perimeter*perimeter)/(area*4*PI);
return eccen;
}
double getDistance(int npoints, double x[], double y[]) {
double distance = 0.0, dx, dy;
int i;
for (i = 0; i < npoints; ++i) {
dx = x[(i+1) % npoints] - x[i];
dy = y[(i+1) % npoints] - y[i];
distance += sqrt(dx * dx + dy * dy);
}
return distance;
}
double poly_area(int length, double x[], double y[]) {
double area = 0.0;
int i, j;
for (i = 0; i < length; ++i) {
j = (i + 1) % length;
area += (x[i] * y[j] - x[j] * y[i]);
}
area = area / 2;
area = (area > 0 ? area : -1 * area);
return (area);
}
int main(int argc, char *argv[]) {
int npoints, point, poly_id, c, k;
int npoints_largest, poly_id_largest;
double x[MAX_PTS], y[MAX_PTS];
double Ax[MAX_POLYS], Ay[MAX_POLYS];
double perimeter, area = 0, eccen, largest_area;
/* ================================Stage 1=================================== */
if(scanf("%d %d", &npoints, &poly_id)) {
for (point = 0; point < npoints; ++point) {
scanf("%lf %lf", &(x[point]), &(y[point]));
}
}
perimeter = getDistance(npoints, x, y);
area = poly_area(npoints, x, y);
eccen = eccentricity(perimeter, area);
printf("\nStage 1\n=======\n");
printf("First polygon is %d\n", poly_id);
printf(" x_val y_val\n");
for (point = 0; point < npoints; ++point) {
printf(" %2.1f %2.1f\n", x[point], y[point]);
}
printf("perimeter = %3.2f m\n", perimeter);
printf("area = %3.2f m^2\n", area);
printf("eccentricity = %3.2f\n", eccen);
/* ================================Stage 2=================================== */
printf("\nStage 2\n=======\n");
for (c=0; c<PER_ROW; c++) {
printf("+-------");
if(c == PER_ROW-1) {
printf("+");
}
}
printf("\n| id | nval | perim | area | eccen |\n");
for (c=0; c<PER_ROW; c++) {
printf("+-------");
if(c == PER_ROW-1) {
printf("+\n");
}
}
printf("| %5d | %5d | %5.2f | %5.2f | %5.2f |\n", poly_id, npoints,
perimeter, area, eccen);
while (scanf("%d %d", &npoints, &poly_id) == 2) {
for(k = 0; k < npoints; k++) {
scanf("%lf %lf", &(x[k]), &(y[k]));
perimeter = getDistance(npoints, x, y);
area = poly_area(npoints, x, y);
eccen = eccentricity(perimeter, area);
}
if (area > largest_area) {
largest_area = area;
poly_id_largest = poly_id;
npoints_largest = npoints;
Ax[k] = x[k]; // here is where I attempt to read the largest area
Ay[k] = y[k]; // into another array.
}
printf("| %5d | %5d | %5.2f | %5.2f | %5.2f |\n", poly_id, npoints,
perimeter, area, eccen);
}
for (c=0; c<PER_ROW; c++) {
printf("+-------");
if(c == PER_ROW-1) {
printf("+\n");
}
}
/* ==============================Stage 3===================================== */
printf("\nStage 3\n=======\n");
printf("Largest polygon is %d\n", poly_id_largest);
printf(" x_val y_val\n");
for (k = 0; k < npoints; ++k) { // trying to loop and
printf(" %2.1f %2.1f\n", Ax[k], Ay[k]); // print the values
} // prints out nothing though?
return 0;
}
如果有人可以指出我的代碼中的錯誤或操作提示,不勝感激!
您需要在最終的for循環中使用npoints_largest變量:
for (k = 0; k < npoints_largest; ++k) {
這是有趣的。
因此,您要從用戶輸入5個面輸入? 那么為什么poly_id_largest這么高?
請先將“ Largest_area”設置為0。
答案不正確,它永遠不會進入此代碼塊。
if (area > largest_area) {
largest_area = area;
poly_id_largest = poly_id;
npoints_largest = npoints;
Ax[k] = x[k]; // here is where I attempt to read the largest area
Ay[k] = y[k]; // into another array.
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.