c - '错误 : expected expression' keeps returning. 我做错了什么？

Question

所以我对 C 编程非常陌生，并且陷入困境。

我正在编写一些代码，从文件中读取某些数据(由我的 read_file 函数定义)。我的任务之一是还隐藏 2 个给定点之间的距离(如 void distance 所示)并将其转换为弧度(如 toRadian 所示)。

但是问题出在第 48 行(在代码中突出显示)，我在其中得到

"error: expected expression chord_length = pow(sin(toRadian(lat_2 - LAT_1)/2) + cos(toRadian

program.c:6:15: note: expanded from macro 'LAT_1'

define LAT_1 −37.798185"

我做错了什么？我就是想不出来。

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

#define LAT_1 -78.98214
#define LONG_1 -7.31600
#define R_PI 3.14159
#define DEGREES 180

int read_file(int i);
void toRadian(double theta);
void distance(double d);

int main()
{
    int i = 0;
    return read_file(i);
}

void toRadian(double theta)
{
    double x = 0;
    x = R_PI/DEGREES;
}

void distance(double d)
{
/* This function is designed to calculate the distance between the check-in 
POI and the reference point provided*/
double dist, angle_distance, chord_length;
char *lat_2, *long_2;

    char length[256];
    char *token[6];

    if (fgets(length, 256, stdin) != NULL) 
    {
        token[0] = strtok(length, " ");
        int i = 0;
        double dist;
        for (i = 1; i < 6; i++)
        {
            lat_2 = token[1];
            long_2 = token[2];
        }

    chord_length = pow(sin(toRadian(lat_2 - LAT_1)/2) + cos(toRadian
    (LAT_1)) * cos(toRadian(lat_2)) * pow(sin(toRadian(long_2 - 
    LONG_1))));

    angle_distance = 2 * atan2(sqrt(chrod_length), sqrt(1 - cord_length));

    dist = 6371 * angle_dist;
}

int read_file(int i) 
{
    /* This function takes the data from the input file,reading and printing the 
    User ID, Location (longitude and latitude), Date, Time, and Distance*/
    char length[256];
    char *token[6];

    if (fgets(length, 256, stdin) != NULL) 
    {
        token[0] = strtok(length, " ");
        int i = 0;
        double dist;
        for (i = 1; i < 6; i++)
            token[i] = strtok(NULL, " "); /*C programming is fun*/
            printf("Stage 1\n==========\n");
            printf("User: #%s\n", token[0]); 
            printf("Location: <%s, %s>\n", token[1], token[2]);
            printf("Date: %s\n", token[3]);
            printf("Time: %s\n", token[4]);
            printf("Distance to reference: %2.2f\n", distance(dist));
    }
    else
    {
        printf("Error opening file. Check file and try again.");
        exit(EXIT_FAILURE);
    }
    return 0;
}

Answer 1

您正在从指针 (lat_2 - LAT_1) 中减去 float 。这没有任何意义。

此外，您将其传递给 toRadian() ，它需要一个 double 值并且不返回任何内容......这都是错误的