没有用于与联动声明功能联动型 [英] Type with no linkage used to declare function with linkage

问题描述

我试图写一个函数，它作为一个参数指针我与的typedef 名为的NodeType 。我依稀明白，的typedef 名称没有关联。我不知道为什么当键入的NodeType 的两个实例似乎是在同一个翻译单元我会得到下面的错误。

I am trying to write a function that takes as a parameter a pointer to a type I created with typedef called NodeType. I dimly understand that typedef names don't have linkage. I am not sure why I would get the following error when both instances of the type NodeType appear to be in the same translation unit.

这里是code：

#include <stdio.h>

int main(){

    typedef struct NodeTag{
            char* Airport;
            NodeTag * Link;                
            } NodeType;


    //Declare print function
    void printList(NodeType *);

    void printList(NodeType * L){
        //set N to point to the first element of L
        NodeType * N = L;         

        //if the list is empty we want it to print ()
        printf("( ");
        //while we are not at the Link member of the last NodeType
        while(N != NULL){
        //get the Airport value printed
            printf("%s", N->Airport);
            //advance N
            N= N->Link;
            if(N != NULL){
            printf(", ");
            }
            else{
             //do nothing
            }
         }

        printf(")");   
    }

return 0;
}

这是我碰到的错误：

linkedlists.c: In function 'int main()':
linkedlists.c: error: type 'NodeType {aka main()::NodeTag} with no linkage used
to declare function 'void printList(NodeType*) with linkage [-fpermissive]

感谢您的帮助！

推荐答案

您的printList 函数主，这是混淆编译器。移动的printList 的体外主是这样的：

Your printList function is defined within the body of main, which is confusing the compiler. Move printList outside the body of main like this:

#include <stdio.h>

typedef struct NodeTag{
        char* Airport;
        NodeTag * Link;                
        } NodeType;


//Declare print function
void printList(NodeType *);

int main(){

    return 0;
}

void printList(NodeType * L){
    //set N to point to the first element of L
    NodeType * N = L;         

    //if the list is empty we want it to print ()
    printf("( ");
    //while we are not at the Link member of the last NodeType
    while(N != NULL){
    //get the Airport value printed
        printf("%s", N->Airport);
        //advance N
        N= N->Link;
        if(N != NULL){
        printf(", ");
        }
        else{
         //do nothing
        }
     }

    printf(")");   
}

在你这样做，得到它来编译，你需要弄清楚如何以及在哪里调用的printList 从内部主。

After you've done this and got it to compile, you'll need to figure out how and where to call printList from within main.

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