C语言链表节点中if(current->yes)条件的含义及判定逻辑咨询

Hey there! Let's break down your two questions clearly using the code you shared:

1. if(current->yes)条件的含义是什么？ #

First, let's recap the struct definition you provided:

typedef struct node { 
    char *question; 
    struct node *no; 
    struct node *yes; 
} node;
node *current;

This node struct is the building block of a binary decision tree—each node holds a question, plus two pointers to child nodes: one for the "no" answer path, and one for the "yes" answer path.

The condition if(current->yes) is checking whether the yes pointer of the current node is not NULL. In C, any non-NULL pointer evaluates to true in a boolean context, while a NULL pointer evaluates to false.

So the full line:

if (current->yes) { current = current->yes; }

means: "If the current node has a valid 'yes' child node (i.e., there's a follow-up question/branch for a 'yes' answer), move the current pointer to that 'yes' child node."

2. 在if条件中，current->yes应判定什么内容？ #

At its core, current->yes is being checked to confirm two key things:

• Validity of the child node: We're verifying that the yes pointer points to an allocated, valid node instance (not NULL). This prevents us from trying to access memory that doesn't exist (which would cause a crash or undefined behavior).
• Existence of a follow-up branch: In a decision tree structure, leaf nodes (nodes that don't have further questions) typically have their yes and no pointers set to NULL. So this check tells us: "Is there a next step in the decision path when the user answers 'yes'?"

Put simply, you're checking if there's a valid "yes" branch to traverse before moving the current pointer to it.

内容的提问来源于stack exchange，提问作者Mody El Sayed