Question

我意识到这个问题经常被问到，但我仍然不明白它是如何运作的。我想尝试将我的文件读入我的结构，在函数内部，并通过指向函数的指针传递结构。我不确定如何编写函数原型。

#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];

}

这个功能看起来像什么？我是否正确假设通过使用指针，struct将自动在main中更新，而不需要在函数中返回一些东西？

该函数是否也不返回任何内容（void），因为指针的使用会自动传递给main？

谢谢！

Answer 1

您的代码已关闭，但填充人体结构的子例程中的指针逻辑不正确。看看以下返工和轻微简化是否有助于您了解如何通过该结构：

#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;
}

使用指针 - 函数传递struct的数组和返回struct的数组

1 个答案: