C 结构声明

Question

我的 C 语法有点问题。我想构建一个结构数组。但是它 returns

expected declaration specifiers or ‘...’ before ‘cities’

这是我的代码

    #include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

struct City {
  int plateNumber;
  char name[32];
  double area;
  int population;
  int populationDensity;
  int cityCenterPopulation;
  char region[32];
  double latitude;
  double longitude;
};

struct City cities[81];
#define Struct_Size sizeof(struct City)

void printCityData(cities[], int i);
void readFile();

void readFile(){
  int fd = open("data.dat", O_RDONLY);
  if(fd<0) {
    printf("Error while opening file!");
    return;
  }
  int i;
  for (i = 0; i < 81; i++) {
    while(read(fd,&cities[i], Struct_Size)>0) {
      printCityData(cities[i],i);
    }
  }

}

void printCityData(cities[], int i) {
  printf("CITIES\n");
  printf("plateNumber: %d\n", cities[i].plateNumber);
  printf("name: %s\n", cities[i].name);
  printf("area: %lf\n", cities[i].area);
  printf("population: %d\n", cities[i].population);
  printf("populationDensity: %d\n", cities[i].populationDensity);
  printf("cityCenterPopulation: %d\n", cities[i].cityCenterPopulation);
  printf("region: %s\n", cities[i].region);
  printf("latitude: %lf\n", cities[i].latitude);
  printf("longitude: %lf\n", cities[i].longitude);
}

int main(int argc, char const *argv[]) {
  readFile();
  return 0;
}

我该如何解决这个问题？

Answer 1

我相信，问题是由于 cities[] 之前

中缺少数据类型造成的

 void printCityData(cities[], int i)

应该是

 void printCityData(struct City cities[], int i)

请记住，cities 是一个变量，而不是数据类型。 FWIW，在前向声明的情况下，你实际上可以省略变量名而不是变量类型。

也就是说，实际上，cities 在这里是一个全局变量，您不需要将其作为参数传递。您可以将函数签名减少为

void printCityData(int i) {

并称其为

 printCityData(i);

Answer 2

问题是你没有提到城市的数据类型，而且你调用函数时使用的数据类型与我假设你想要的不同。我已经进行了所需的更改：

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

struct City {
  int plateNumber;
  char name[32];
  double area;
  int population;
  int populationDensity;
  int cityCenterPopulation;
  char region[32];
  double latitude;
  double longitude;
};

struct City cities[81];
#define Struct_Size sizeof(struct City)

void printCityData(struct City cities[], int i); //cities is an array of struct City
void readFile();

void readFile(){
  int fd = open("data.dat", O_RDONLY);
  if(fd<0) {
    printf("Error while opening file!");
    return;
  }
  int i;
  for (i = 0; i < 81; i++) {
    while(read(fd,&cities[i], Struct_Size)>0) {
      printCityData(cities,i);
    }
  }

}

void printCityData(struct City cities[], int i) {
  printf("CITIES\n");
  printf("plateNumber: %d\n", cities[i].plateNumber);
  printf("name: %s\n", cities[i].name);
  printf("area: %lf\n", cities[i].area);
  printf("population: %d\n", cities[i].population);
  printf("populationDensity: %d\n", cities[i].populationDensity);
  printf("cityCenterPopulation: %d\n", cities[i].cityCenterPopulation);
  printf("region: %s\n", cities[i].region);
  printf("latitude: %lf\n", cities[i].latitude);
  printf("longitude: %lf\n", cities[i].longitude);
}

int main(int argc, char const *argv[]) {
  readFile();
  return 0;
}

C 结构声明

C Struct Declaration

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arrays

struct

function-calls