C函數不返回

我正在編寫一個程序，它必須使用函數，並且我沒有收到任何語法錯誤，並嘗試了多次嘗試更改，但沒有成功。該函數沒有正確保存到.out文件中。C函數不返回

下面是代碼：

/* LAB13, functions          */ 
/* Given the number of sides of an n-side regular polygon */ 
/* and the radius of the circle, find the perimeter and */ 
/* area of the polygon         */ 

#include <stdio.h> 
#include <stdlib.h> 
#include <math.h> 
#define IN_FILE "lab13.dat" 
#define OUT_FILE "lab13.out" 

/* function prototypes */ 
double get_perimeter(double n, double radius); 
double get_area(double n, double radius); 

int main(void) 
{ 
     double n;    /* number of sides   */ 
     double radius;   /* radius of the circle  */ 
     double area;   /* area of the polygon  */ 
     double perimeter;  /* perimeter of the polygon */ 

    FILE * data_in;  /* input file pointer */ 
    FILE * data_out; /* output file pointer */ 

    /* Open the two required files */ 
    data_in = fopen(IN_FILE, "r"); 
    if (data_in == NULL) 
    { 
     printf("Error on fopen file %s \n", IN_FILE); 
     exit(EXIT_FAILURE); 
    } 

    data_out = fopen(OUT_FILE, "w"); 
    if (data_out == NULL) 
    { 
     printf("Error on fopen file %s \n", OUT_FILE); 
     exit(EXIT_FAILURE); 
    } 
    /* Print headers */ 
    fprintf(data_out, "\nScott _________. Lab13. \n\n"); 
    fprintf(data_out, " Number Of Sides  Radius Perimeter  Area \n"); 
    fprintf(data_out, " of Polygon  of Circle of Polygon of Circle \n"); 
    fprintf(data_out, "---------------- --------- ---------- --------- \n"); 
    while ((fscanf(data_in, "%lf%lf", &n, &radius))== 2) 
     { 
      perimeter = get_perimeter(n, radius); 
      area  = get_area(n, radius); 
      fprintf(data_out,"%8i %17.3f %11.3f %10.3f\n", 
       n, radius, perimeter, area); 
     } 
    printf("\n"); 
    fclose(data_in); 
    fclose(data_out); 
    return EXIT_SUCCESS; 
} 

/*-----------------------------------------------------------*/ 
double get_perimeter(double n, double radius) 
{ 
    double perimeter; 

    perimeter = 2 * n * radius * (sin(M_PI/n)); 
    return perimeter; 
} 

/*-----------------------------------------------------------*/ 
double get_area(double n, double radius) 
{ 
    double area; 

    area = 0.5 * n * (radius*radius) * (sin(2*M_PI)/n); 
    return area; 
} 

/*-----------------------------------------------------------*/

，它是從抓住lab13.dat文件是：

3.0 16.5
5.0 9.1
7.0 11.5
The output from running the program

來源

2016-11-08 Scott

'fprintf'格式'％8i'對'double n'不好;' –

您對計算沒有疑問。你有一個關於你面臨困難的故事。你需要學習[如何調試小程序]（https://ericlippert.com/2014/03/05/how-to-debug-small-programs/） – StoryTeller

我甚至不理解'n'的作用 - 周長和麪積函數只需要一個參數：半徑。 –

你'n，這是一個double，使用格式%8i，期望int。如果要打印double，但禁止任何可能的非整數部分，請使用0精度，如%8.0f中所述。

來源

2016-11-08 20:34:46 hobbs

你是問題是在fprintf。

fprintf(data_out,"%8i %17.3f %11.3f %10.3f\n", n, radius, perimeter, area);

我不是你想要的格式說明符，使用f。可能是輸入錯誤

來源

2016-11-08 20:40:21

C函數不返回

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