Question

我正在尝试解决未解决的外部问题（link2019错误）。 StackOverflow上有很多关于这个问题的帖子，但要么我不理解错误，要么我对它视而不见。

错误是由我的generate_maze函数引起的（特别是rand_neighbor（）调用，对吗？）但我的理解是这些都是“已解决”。

我稍微截断了代码，因为它非常详细。我希望这是合适的。

void generate_maze (Vector<int> &coords, Grid<bool> &included, Maze &m);

int main() {

    Grid<bool> included = initialize_grid();
    Vector <int> coords = rand_coords();
    Vector <int> current_point = coords;

    generate_maze(coords, included, m);
    return 0;
}

void generate_maze (Vector<int> &coords, Grid<bool> &included,  Maze &m) {
    while (gridIsTrue == false) {
    Vector<int> neighbor = rand_neighbor(coords, included);
    pointT neighborpoint = {neighbor[0], neighbor[1]};
    pointT current_point = {coords[0], coords[1]};
    if (included.get(neighbor[0], neighbor[1]) == false) {m.setWall(current_point, neighborpoint, false); included.set(neighbor[0], neighbor[1], true); current_point = neighborpoint;}
    }
}

Vector<int> rand_neighbor(Vector<int> &coords, Grid<bool> &included) {
    while (1) {
        int randomint;
        randomint = randomInteger(1,4);
        if (randomint == 1) {if (included.inBounds(coords[0], coords[1]+1)) {coords[1] = coords[1]+1; break;}}
        if (randomint == 2) {if (included.inBounds(coords[0], coords[1]-1)){coords[1] = coords[1] -1; break;}}
        if (randomint == 3) {if (included.inBounds(coords[0] -1, coords[1])){coords[0] = coords[0] -1; break;}}
        if (randomint == 4) {if (included.inBounds(coords[0] +1, coords[1])){coords[0] = coords[0] + 1; break;}}
                }
        return coords;

错误：

error LNK2019: unresolved external symbol "class Vector<int> __cdecl rand_neighbor(class Vector<int>,class Grid<bool> &)" (?rand_neighbor@@YA?AV?$Vector@H@@V1@AAV?$Grid@_N@@@Z) referenced in function "void __cdecl generate_maze(class Vector<int> &,class Grid<bool> &,class Maze &)" (?generate_maze@@YAXAAV?$Vector@H@@AAV?$Grid@_N@@AAVMaze@@@Z)
1>C:\Users\com-user\Desktop\New folder\maze\assign3-maze-PC\Maze\Debug\Maze.exe : fatal error LNK1120: 1 unresolved externals

Answer 1

使用漂亮的网络c ++ demangler here，您可以看到未定义的引用?rand_neighbor@@YA?AV?$Vector@H@@V1@AAV?$Grid@_N@@@Z实际上意味着class Vector __cdecl rand_neighbor(class Vector,class Grid &)。您的错误消息中缺少参数。

现在，您是否看到声明与函数定义之间的区别？

class Vector __cdelc rand_neighbor(class Vector,class Grid &);
Vector<int> rand_neighbor(Vector<int> &coords, Grid<bool> &included) { /* ... */}

让我稍微规范化一下：

Vector<int> rand_neighbor(Vector<int>, Grid<bool> &);
Vector<int> rand_neighbor(Vector<int> &, Grid<bool> &) { /* ... */}

你忘记了函数原型中的引用（&）！因此，您的定义具有不同的功能。

Answer 2

正如链接器告诉你的那样，问题出在rand_neighbor()函数上。你为它提供了声明（如果你没有，你会得到编译器错误而不是链接器错误），但你还没有提供定义。

未解决的外部链接2019混乱

2 个答案: