krahets/hello-algo · error · Error

栈为空

Error message

栈为空

What it means

Thrown by ArrayStack.pop() ('栈为空' / stack is empty) when the underlying array has length 0. pop() calls Array.pop which would return undefined, but the explicit guard rejects that as an error to avoid returning undefined where a number is expected.

Source

Thrown at codes/typescript/chapter_stack_and_queue/array_stack.ts:31

    /* 获取栈的长度 */
    get size(): number {
        return this.stack.length;
    }

    /* 判断栈是否为空 */
    isEmpty(): boolean {
        return this.stack.length === 0;
    }

    /* 入栈 */
    push(num: number): void {
        this.stack.push(num);
    }

    /* 出栈 */
    pop(): number | undefined {
        if (this.isEmpty()) throw new Error('栈为空');
        return this.stack.pop();
    }

    /* 访问栈顶元素 */
    top(): number | undefined {
        if (this.isEmpty()) throw new Error('栈为空');
        return this.stack[this.stack.length - 1];
    }

    /* 返回 Array */
    toArray() {
        return this.stack;
    }
}

/* Driver Code */
/* 初始化栈 */
const stack = new ArrayStack();

View on GitHub (pinned to 69932aed18)

Solutions

1. Guard with isEmpty(): if (!stack.isEmpty()) stack.pop().
2. Use while (!stack.isEmpty()) for drain loops.
3. Ensure balanced push/pop counts; audit sentinel handling.

Example fix

// before
const top = stack.pop(); // throws when empty
// after
if (!stack.isEmpty()) {
    const top = stack.pop();
}

function safePop(stack) {
  return stack.isEmpty() ? undefined : stack.pop();
}

null

null

When it happens

Trigger: Calling pop() on a freshly-constructed or fully-drained stack; an unbalanced push/pop sequence (more pops than pushes).

Common situations: Evaluation loops (expression evaluators, backtracking) that pop one extra sentinel or operator; recursion-elimination via an explicit stack that pops past empty.

Related errors

• 栈为空
• Stack is empty
• Stack is empty
• стек пуст
• стек пуст

AI-assisted analysis of krahets/hello-algo@69932aed18 (2026-08-13). Data as JSON: /api/errors/5fead45f9247928e. Report an issue: GitHub.