我正在制作一个程序来发现从一个顶点到另一个顶点的最佳路径。好吧，我创建顶点，为邻居列表分配内存。当我在两个顶点之间创建连接时，我重新分配列表的内存以向邻居列表添加一个顶点。它似乎在前两次工作，但在第三次它崩溃并给我信号“SIGABRT”。我找不到任何论坛的问题的解决方案。这是我的代码：
typedef struct vertex{
char* name;
Vertex** neighbors;
float x, y;
}Vertex;
Vertex* create_vertex(char* name, float x, float y){
Vertex* vertex = (Vertex*) malloc(sizeof(Vertex));
vertex->x = x;
vertex->y = y;
vertex->name = (char*) malloc(sizeof(char)*strlen(name) + 1);
strcpy(vertex->name, name);
vertex->neighbors = (Vertex**) malloc(sizeof(Vertex*));
vertex->neighbors[0] = NULL;
return vertex;
}
void creates_connection(Vertex* v1, Vertex* v2){
if(areNeighbors(v1, v2)){
printf("Vertices ja sao vizinhos");
return;
}
Vertex** real;
if(v1->neighbors[0] == NULL){
real = (Vertex**) realloc(v1->neighbors, sizeof(Vertex*)+1);
if(real != NULL){
v1->neighbors = real;
v1->neighbors[0] = v2;
v1->neighbors[1] = NULL;
}else printf("Nao foi possivel realocar memoria");
}else{
Vertex* aux = v1->neighbors[0];
int i = 0;
while(aux != NULL){
aux = v1->neighbors[i];
i++;
}
real= (Vertex**) realloc(v1->neighbors, (sizeof(Vertex*))*(i+1));
if(real!= NULL){
v1->neighbors= real;
v1->neighbors[i] = v2;
v1->neighbors[i+1] = NULL;
}else printf("Nao foi possivel realocar memoria");
}
if(v2->neighbors[0] == NULL){
real = (Vertex**) realloc(v2->neighbors, sizeof(Vertex*));
if(real != NULL){
v2->neighbors = realocado;
v2->neighbors[0] = v1;
v2->neighbors[1] = NULL;
}
}else{
Vertex* aux = v2->neighbors[0];
int i = 0;
while(aux != NULL){
aux = v2->neighbors[i];
i++;
}
//HERE, BELLOW, IT CRASHES, DOESN'T PASS TO THE IF
real = (Vertex**) realloc(v2->neighbors, (sizeof(Vertex*))*(i+1));
if(real != NULL){
v2->neighbors = real;
v2->neighbors[i] = v1;
v2->neighbors[i+1] = NULL;
}else printf("Nao foi possivel realcoar memoria");
}
}
我不知道这是否是最好的方式来做我正在做的事情，我接受建议，但我也想了解发生了什么，我的意思是，为什么这个SIGABRT正在发生。
答案 0 :(得分：0)
这个答案专注于指出（部分）发布代码中的问题。最后，这个答案包含了一个代码更改的建议，该代码更改将适用于您当前的设计。如果您愿意进行重新设计，请查看@wildplasser
的答案这里有一个问题
if(v1->neighbors[0] == NULL){
real = (Vertex**) realloc(v1->neighbors, sizeof(Vertex*)+1);
^^^^
This only increase with 1 byte
but you want 1 pointer
在这里
if(v2->neighbors[0] == NULL){
real = (Vertex**) realloc(v2->neighbors, sizeof(Vertex*));
^^^^
No increase at all
此处还有一个问题：
Vertex* aux = v1->neighbors[0];
int i = 0;
while(aux != NULL){
aux = v1->neighbors[i];
i++;
}
real= (Vertex**) realloc(v1->neighbors, (sizeof(Vertex*))*(i+1));
由于你的设计要求数组的末尾总是有一个NULL指针，你需要让i从1开始，即
int i = 1;
当你写出一边分配的内存时，这部分也有问题 - 记住索引从零开始：
real= (Vertex**) realloc(v1->neighbors, (sizeof(Vertex*))*(i+1));
if(real!= NULL){
v1->neighbors= real;
v1->neighbors[i] = v2;
v1->neighbors[i+1] = NULL; // UPS... write outside allocated memory
// Writing to [i+1] requires that you
// have i+2 pointers but you only
// have i+1
有趣的是，当第一个指针为NULL时，您不需要处理这两个特殊情况。 else中的代码也可以处理第一个指针为NULL的情况。
所以这段代码：
if(v1->neighbors[0] == NULL){
real = (Vertex**) realloc(v1->neighbors, sizeof(Vertex*)+1);
if(real != NULL){
v1->neighbors = real;
v1->neighbors[0] = v2;
v1->neighbors[1] = NULL;
}else printf("Nao foi possivel realocar memoria");
}else{
Vertex* aux = v1->neighbors[0];
int i = 0;
while(aux != NULL){
aux = v1->neighbors[i];
i++;
}
real= (Vertex**) realloc(v1->neighbors, (sizeof(Vertex*))*(i+1));
if(real!= NULL){
v1->neighbors= real;
v1->neighbors[i] = v2;
v1->neighbors[i+1] = NULL;
}else printf("Nao foi possivel realocar memoria");
}
可以简化为
Vertex* aux = v1->neighbors[0];
int i = 1; // NOTICE: Use 1 instead of 0
while(aux != NULL){
aux = v1->neighbors[i];
i++;
}
real= (Vertex**) realloc(v1->neighbors, (sizeof(Vertex*))*(i+1));
if(real!= NULL){
v1->neighbors= real;
v1->neighbors[i-1] = v2; // NOTICE: i-1
v1->neighbors[i] = NULL; // NOTICE: i
}else printf("Nao foi possivel realocar memoria");
这也适用于您处理v2
答案 1 :(得分：0)
filterNot()