Question

我正在寻找约一天如何解决我的问题。我找到类似于我的问题的解决方案，但是当我应用更改错误时：error: request for member 'mark' in something not a structure or union一直显示。

到目前为止我所拥有的是struct，我想在函数调用中对其进行初始化。

编辑我的代码：

typedef struct student * Student;

struct student {
    char *mark; /* or array[2] like array[0] = 'A' , array[1] = 'B' */
    int age;
    int weight;
};

typedef enum{
    MEMORY_GOOD,
    MEMORY_BAD} Status; 

int main(int argc, char* argv[]) {

    int status = 0; 

    Student john  


    /* Function  call to allocate memory*/

    status = initMemory(&john);

    return(0);
}


Status initMemory(Student *_st){
     _st =  malloc(sizeof(Student));


    printf("Storage size for student : %d \n", sizeof(_st));

    if(_st == NULL)
    {
        return MEMORY_BAD;
    }   

    _st->mark = malloc(2*sizeof(char)); /* error: request for member 'mark' in something not a structure or union */

    return MEMORY_GOOD; 
}

Answer 1

尽量避免在代码中使用太多*，

在进行一些更改后能够运行它，请参阅下一行中的ideone链接。

http://ideone.com/Ow2D2m

#include<stdio.h>
#include<stdlib.h>
typedef struct student* Student; // taking Student as pointer to Struct
int initMemory(Student );
struct student {
char* mark; /* or array[2] like array[0] = 'A' , array[1] = 'B' */
int age;
int weight;
};

typedef enum{
    MEMORY_GOOD,
    MEMORY_BAD} Status; 

int main(int argc, char* argv[]) {

    Status status;

    Student john;  /* Pointer to struct */

  /* Function  call to allocate memory*/
    status = initMemory(john);
    printf("got status code %d",status);
}

int initMemory(Student _st){
     _st =  (Student)malloc(sizeof(Student));

    printf("Storage size for student : %d \n", sizeof(_st));
    if(_st == NULL)
    {
        return MEMORY_BAD;
    }   else {
        char* _tmp = malloc(2*sizeof(char)); /* error: request for member     'mark' in something not a structure or union */
    _st->mark = _tmp;
    return MEMORY_GOOD; 
    }
 }

Answer 2

只需替换

_st->mark = malloc(2 * sizeof(char));

使用

(*_st)->mark = malloc(2 * sizeof(char));

_st 是指针，内容是结构的地址，所以......

1）首先你需要取消引用 _st ，然后...... 2）第二，你得到值，你指向字段标记

这就是全部！

为函数内部的struct数组指针分配内存

2 个答案: