传递和返回结构C

因此，我遇到了这样的问题：我只在main中获取错误代码，1当我将结构保存在头文件中时，结构已经被定义，2我使用的是不兼容的指针类型

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "functDefs.h"
#include "writeToFile.c"
#include "readFile.c"
#include "inputContactInfo.c"
#include "contactInfoStruct.h"

int main(void) {

    int i = 0;
    char *ynAns;
    struct contactId *contactInfo;
    contactInfo = malloc(sizeof(struct contactId));

    do {
            if(ynAns != NULL) {
                    free(ynAns);
            }
            ynAns = malloc(sizeof(char) * 5);
            printf("\nDo you wish to enter a new contact (Yes or No)?: ");
            fgets(ynAns, 5, stdin);
            ynAns[(strlen(ynAns) - 1)] = '\0';
            if (strcmp(ynAns, "Yes") == 0) {
                    printf("\n");
                    contactInfo = realloc(contactInfo, sizeof(struct contactId) * (i + 1));
                    contactInfo[i] = inputContactInfo();
                    i++;
            }

    } while(strcmp(ynAns, "No") != 0);

    writeToFile(contactInfo, i);

    readFile(i);

    free(contactInfo);
    return 0;
}

这是结构头文件：

struct contactId {
    char firstName[20];
    char lastName[20];
    char companyName[50];
    char phoneNumber[15];
    char email[50];
};

我会遇到如下错误：

IOlist.c: In function ‘main’:
IOlist.c:28:40: error: incompatible types when assigning to     type ‘struct contactId’ from type ‘struct contactId *’
                     contactInfo[i] = inputContactInfo();
                                    ^
IOlist.c:34:21: warning: passing argument 1 of ‘writeToFile’  from incompatible pointer type
     writeToFile(contactInfo, i);
                 ^
In file included from IOlist.c:5:0:
writeToFile.c:7:6: note: expected ‘struct contactId *’ but  argument is of type ‘struct contactId *’
void writeToFile(struct contactId *contInfo, int numContacts)   {
     ^

还有这些错误：

In file included from IOlist.c:5:0:
writeToFile.c:7:6: error: conflicting types for ‘writeToFile’
void writeToFile(struct contactId *contInfo, int numContacts)  {
     ^
In file included from IOlist.c:4:0:
functDefs.h:1:6: note: previous declaration of ‘writeToFile’  was here
void writeToFile(struct contactId *contInfo, int numContacts);
     ^
In file included from readFile.c:4:0,
             from IOlist.c:6:
contactStruct.h:1:8: error: redefinition of ‘struct contact’
struct contact {
       ^
In file included from writeToFile.c:4:0,
             from IOlist.c:5:
contactStruct.h:1:8: note: originally defined here
 struct contact {
        ^

---

函数inputContactInfo返回指向struct的指针。但它试图返回n指针的地方是一个结构。您需要声明struct contactId**contactInfo，为每个元素分配内存，然后才能正确地将指针分配给contactInfo[i]。

这些“错误”的部分原因是，在声明writeToFile函数之前，您没有确保编译器知道struct contactId存在。原型中的类型仅在原型中已知。只需添加line struct contactId；在函数头的顶部，问题可能会消失，或者会有一组不同的问题需要处理。

In file included from IOlist.c:5:0:
writeToFile.c:7:6: error: conflicting types for ‘writeToFile’
void writeToFile(struct contactId *contInfo, int numContacts)  {
     ^
In file included from IOlist.c:4:0:
functDefs.h:1:6: note: previous declaration of ‘writeToFile’  was here
void writeToFile(struct contactId *contInfo, int numContacts);
     ^
In file included from readFile.c:4:0,
             from IOlist.c:6:
contactStruct.h:1:8: error: redefinition of ‘struct contact’
struct contact {
       ^
In file included from writeToFile.c:4:0,
             from IOlist.c:5:
contactStruct.h:1:8: note: originally defined here
 struct contact {
        ^