指向struct内部的struct的双指针 [英] double pointer to struct inside struct
本文介绍了指向struct内部的struct的双指针的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
如何访问结构指针中的双重指针? 使用下面的代码,调用addBow()会给我一个Segmentation Fault(核心转储)错误
How can i access to a duble pointer in a struct pointer?? with the code bellow, calling addBow() give me a Segmentation fault (core dumped) error
typedef struct
{
int size;
tCity **cities;
}tGraph;
//para iniciar el grafo
void initGraph(tGraph *graph, int size)
{
graph = (tGraph*)malloc(sizeof(tGraph));
graph->cities = (tCity**)malloc(sizeof(tCity*) * size);
graph->size = size;
}
//agrega un arco entre ciudades
void addBow(tGraph *graph, int id, tCity *city)
{
if ( graph->cities[id] == NULL )
{
graph->cities[id] = city;
}
else
{
tCity *cur = graph->cities[id];
while ( getNext(cur) != NULL )
{
cur = getNext(cur);
}
setNext(cur, city);
}
}
这是graph-> cities [id] ??
which is the correct syntax for graph->cities[id]??
谢谢
解决方案: 编辑initGraph解决了该问题,因为未分配内存
SOLUTION: editing the initGraph solve the problem since the memory wasn't allocated
tGraph* initGraph(int size)
{
tGraph *graph = (tGraph*)malloc(sizeof(tGraph));
graph->cities = (tCity**)malloc(sizeof(tCity*) * size);
graph->size = size;
return graph;
}
推荐答案
您应该让initGraph()接受(**图形)或返回图形.由于图的malloc地址是initGraph的本地地址.
You should either have initGraph() take (**graph) or return the graph. Since the malloc address of graph is local to initGraph.
类似的东西:
void initGraph(tGraph **graph, int size)
{
tgraph *temp;
temp = (tGraph*)malloc(sizeof(tGraph*));
temp->cities = (tCity**)malloc(sizeof(tCity*) * size);
temp->size = size;
*graph = temp;
}
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