Question

我正在用C编写程序，我有一些我不理解的错误。这是我的main：

#include "res.h"
#include <stdio.h>
#include <conio.h>

int main(){
Kitchen List;
char *name = "Productname";
float price = 5.6, qwan = 4;
List.head = NULL;

CreateProduct(name, price, qwan, &List);



getch();
return 0;
}

这是我的头文件：

#include <stdio.h>
#ifndef _res
#define _res


typedef struct Portion{             
    char *pName;
    float pPrice;
    float pQuantity;
    Portion *next;
}Portion;

typedef struct Kitchen{            
    Portion *head;
    int size;
}Kitchen;

void get_lost(char *string);
/*
Name : get_lost
Output: Void
Algorithem: 
*/
void CreateProduct(char *name, float price, float quantity, Kitchen *List);
/*
Name : CreateProduct
Output: Void
Algorithem:
*/

#endif

这是我的res.c：

#include "res.h"

//Prints an error msg.
void get_lost(char *string){
    printf("%s", string);
    getch();
    exit(1);
}

//Creates nodes of portion type.
void CreateProduct(char *name, float price, float quantity, Kitchen *List){
    Portion *temp = List->head;

    Portion *newPortion = (Portion*)malloc(sizeof(Portion));               //Allocating memory for new node.
    if (newPortion == NULL)
        get_lost("Memory allocation has failed!");

    newPortion->pName = (char*)malloc(sizeof(char)*strlen(name) + 1);     //Allocating memory for portion name.
    if (newPortion == NULL)
        get_lost("Memory allocation has failed!");
    strcpy(newPortion->pName, name);                                      //Copy name of product to pName.

    newPortion->pPrice = price;                                          //Initializing Portion price.
    newPortion->pQuantity = quantity;                                    //Initialzing Portion quantity.


    while (List->head != NULL)
    {                                                                   //We check if portion is already in the list.
        if (strcmp(List->head->pName, newPortion->pName))
        {
            printf("This portion already exists.");
            return;
        }
        List->head = List->head->next;
    }

    List->head = temp;                                                   //We saved the head of the list in a tempoaray variable.
    newPortion->next = List->head;                                      //Add newPortion to the list.
    List->head = newPortion;
    List->size++;                                                       //We count the number of portions in the list.
}

我收到以下错误，我不明白为什么：

Error   26  error C2143: syntax error : missing ')' before '*'
Error   27  error C2081: 'Kitchen' : name in formal parameter list illegal  
Error   28  error C2143: syntax error : missing '{' before '*'

有人可以帮我找出问题所在吗？

Answer 1

变化：

typedef struct Portion{             
    char *pName;
    float pPrice;
    float pQuantity;
    Portion *next;
}Portion;

为：

typedef struct Portion{             
    char *pName;
    float pPrice;
    float pQuantity;
    struct Portion *next; // <<<
}Portion;

另请注意you shouldn't cast the result of malloc in C，所以要改变，例如

Portion *newPortion = (Portion*)malloc(sizeof(Portion));

为：

Portion *newPortion = malloc(sizeof(Portion));

或者最好：

Portion *newPortion = malloc(sizeof *newPortion);

Answer 2

你犯了一个常见的错误。 typedef struct Portion{ };是一个自引用结构，因为它有*next类型的指针struct Portion 因此，当您将结构声明为

时

typedef struct Portion{             
    char *pName;
    float pPrice;
    float pQuantity;
    Portion *next;
}Portion;

编译器还不知道Portion是什么类型。

所以你必须将其声明为，

typedef struct Portion{
    char *pName;
    float pPrice;
    float pQuantity;
    struct Portion *next;
}Portion;

我更愿意将其定义为Portion_t而不是Portion。对于typedef和struct来说，是否应该使用union这是一个非常矛盾的问题，因为作为独立的开发者，我需要知道它是否是struct或union。

编译器错误“正式参数列表中的名称非法”

2 个答案: