Question

此代码用于使用adjacency-list创建图形。
graphnode是垂直链表的每个元素的水平链表的结构，而#include<iostream> using namespace std; struct node //struct { struct node *next; char value; }; struct graphnode { struct node *start; struct graphnode *down; char value; int count; }; graphnode * creategraphnode(char val) { struct graphnode *newnode=new graphnode; newnode->start=NULL; newnode->down=NULL; newnode->value=val; newnode->count=0; return newnode; } node *createnode(char val) { struct node *newnode=new node; newnode->next=NULL; newnode->value=val; } void insertgraphnode(char value,graphnode *graph) { struct graphnode *newnode=creategraphnode(value); if(graph==NULL) { graph=newnode; } else { graphnode *temp=graph; while(temp->down) temp=temp->down; temp->down=newnode; } } void insertnode(graphnode *graph) { char val; struct node *temp=graph->start; cout<<"What is the outdegree of "<<graph->value; cin>>graph->count; cout<<"\nEnter"<<graph->count<<" nodes separated by space:"; for(int i=1;i<=graph->count;i++) { cin>>val; node* newnode=createnode(val); temp=newnode; temp=temp->next; } } void display(struct graphnode *graph) { if(graph==NULL) { cout<<"\nNo data to display"; return; } struct graphnode *temp=graph; while(temp) { struct node *temp1=temp->start; cout<<temp->value<<"=>> "; if(temp1==NULL) { continue; } else { while(temp1) { cout<<temp1->value<<"-> "; temp1=temp1->next; } } cout<<"/\n"; } } int main() { struct graphnode *graph=NULL; int totalnodes; char val; cout<<"\nHow many nodes does the graph contain? : "; cin>>totalnodes; cout<<"\nEnter "<<totalnodes<<" space separated nodes : "; for(int i=1;i<=totalnodes;i++) { cin>>val; insertgraphnode(val,graph); } struct graphnode *temp=graph; while(temp->down) { insertnode(temp); temp=temp->down; } display(graph); return 0; }是垂直链表的结构。

代码正在正确编译，但是当给出第一个输入时，它会在它之后显示分段错误。

def move_chars(s, index):
    to_index = s.find('__')                # index of destination underscores
    chars = list(s)                        # make mutable list
    to_move = chars[index:index+2]         # grab chars to move
    chars[index:index+2] = '__'            # replace with underscores
    chars[to_index:to_index+2] = to_move   # replace underscores with chars
    return ''.join(chars)                  # stitch it all back together

print(move_chars('ABAB__AB', 0))
print(move_chars('__ABABAB', 3))

Answer 1

如果我没错，你的代码至少有三个问题。

1）您的createnode()不会返回创建的节点;添加return newnode;

2）你的insertgraphnode()没有改变调用函数中的第二个参数;所以，当你在main()

中调用它时

insertgraphnode（VAL，曲线图）;

graph是NULL;在insertgraphnode()内你更改了值，但在函数graph之外仍然是NULL;永远。这会导致分段错误。

您可以解决此更改insertgraphnode()，因此第二个参数是指向指针并传递&graph。

另一种解决方案是修改insertgraphnode()以返回graph值

graphnode *  insertgraphnode(char value,graphnode *graph)
{
    struct graphnode *newnode=creategraphnode(value);
    if(graph==NULL)
    {
        graph=newnode;
    }
    else
    {
        graphnode *temp=graph;
        while(temp->down)
            temp=temp->down;
        temp->down=newnode;
    }
    return graph;
}

以这种方式调用它

graph = insertgraphnode(val,graph);

3）while中的display()进入循环，因为您不会更改temp

的值

为什么我的代码中出现分段错误（核心转储）错误？

1 个答案: