使用指針傳遞結構體數組並返回結構體數組-函數

Question

我知道這個問題經常被問到，但是我仍然不太了解它是如何工作的。 我想嘗試將文件讀入函數內部的結構中，並通過指向函數的指針傳遞結構。 我不確定如何編寫函數原型。

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

#define MAX 90
#define STR 200
#define MAXLEN 40

struct human {
    char name[MAXLEN];
    char surname[MAXLEN];
    int age;
    float weight;
};
int main(int argc, char *argv[]) {
    char *dlim= " ", *end = "\n";
    char *string;
    string = (char *)malloc(sizeof(char) * STR);
    int i = 0, j = 0;
    struct human *man = malloc(sizeof(struct human) * MAX);

    FILE *fin = fopen("data.txt", "r");
    if (fin == NULL) {
        printf("Cannot open file\n");
        exit(0);
    }
    while (fgets (string, STR, fin)){
        read (string, &man[i], dlim, end);
        i++;
    }
    fclose(fin);

    free(string);
    free(man);

  return 0;
}

struct human *man read(char *fstring, struct *man, char *div, char *end){
   int i=0;
   char *tok;

        tok = strtok(string, dlim);
        strcpy(man[i].name, tok);

        tok = strtok(NULL, dlim);
        strcpy(man[i].surname,tok);

        tok = strtok(NULL, dlim);
        man[i].age = atoi(tok);

        tok = strtok(NULL, end);
        man[i].weight = atof(tok);

   return man[i];

}

該功能看起來像什么？ 我是否正確地假設通過使用指針，該結構將在main中自動更新，而無需在函數中返回任何內容？

由於使用指針會自動傳遞給main，因此函數還可以不返回任何內容（無效）嗎？

謝謝！

Answer 1

您的代碼已關閉，但是子程序中填充人為結構的指針邏輯不正確。 看看下面的返工和略微的簡化是否可以幫助您了解如何通過結構：

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

#define MAXIMUM_HUMANS 90
#define MAXIMUM_INPUT_STRING_LENGTH 200
#define MAXIMUM_STRING_LENGTH 40

struct human {
    char name[MAXIMUM_STRING_LENGTH];
    char surname[MAXIMUM_STRING_LENGTH];
    int age;
    float weight;
};

void initialize_human(char *string, struct human *man, char *delimiter, char *end) {
    char *token;

    token = strtok(string, delimiter);
    strcpy(man->name, token);

    token = strtok(NULL, delimiter);
    strcpy(man->surname, token);

    token = strtok(NULL, delimiter);
    man->age = atoi(token);

    token = strtok(NULL, end);
    man->weight = atof(token);
}

int main(int argc, char *argv[]) {
    char *dlim= " ", *end = "\n";
    char string[MAXIMUM_INPUT_STRING_LENGTH];
    struct human humans[MAXIMUM_HUMANS];

    FILE *fin = fopen("data.txt", "r");

    if (fin == NULL) {
        fprintf(stderr, "Cannot open file\n");
        exit(1);
    }

    int population; // after loop, this contains total body count

    for (population = 0; fgets(string, MAXIMUM_INPUT_STRING_LENGTH, fin); population ++) {
        initialize_human(string, &humans[population], dlim, end);
    }

    printf("population: %d\n", population);
    printf("last added: %s who weighs %f\n", humans[population - 1].surname, humans[population - 1].weight);  // test if we loaded it up correctly

    fclose(fin);

    return 0;
}