代码的78,79行为啥不能用stoi代替呢? 自己一旦用这代替了,就报错了.

Question

题目是https://www.luogu.com.cn/problem/UVA101

1.如果使用stringstream,则可以正常运行,如下图.

2.如果使用stoi则会抛出异常.如下图

 

 

3.完整代码如下

#include<bits/stdc++.h>
using namespace std;
vector<int> block[30];
int n;
void init() {//对木块进行初始化 
	for (int i = 0; i < n; i++) {
		block[i].push_back(i);
	}
}

void loc(int num, int& pile, int& height) {//对木块进行定位 以引用的形式返回堆和高度. 
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < block[i].size(); j++) {
			if (block[i][j] == num) {
				pile = i;
				height = j;

				return;
			}
		}

	}
}

void goback(int num) {//将num上方的木块进行归位 
	int pile, height;
	pile = 0;
	height = 0;
	loc(num, pile, height);

	for (int i = height + 1; i < block[pile].size(); i++) {
		int temp = block[pile][i];
		block[temp].push_back(temp);
	}
	block[pile].resize(height + 1);//重新 指定大小. 

}

void move(int num1, int num2) //将num1和其上方的木块放到num2上
{
	int pile1, height1, pile2, height2;
	pile1 = 0;
	height1 = 0;
	pile2 = 0;
	height2 = 0;

	loc(num1, pile1, height1);
	loc(num2, pile2, height2);
	for (int i = height1; i < block[pile1].size(); i++) {
		block[pile2].push_back(block[pile1][i]);
	}
	block[pile1].resize(height1);
}

void print() {
	for (int i = 0; i < n; i++) {
		cout << i << ":" << " ";
		for (int j = 0; j < block[i].size(); j++) {
			cout << block[i][j] << " ";
		}
		cout << endl;
	}
}

void solve() {
	string str, str2, str3, str4;
	int pile1 = 0, pile2 = 0, height1 = 0, height2 = 0,temp1,temp2;
	stringstream sm;

	while (cin >> str && str != "quit") {
		cin >> str2 >> str3 >> str4;
		sm.clear();
		sm << str2;
		sm >> temp1;
		sm.clear();
		sm << str4;
		sm >> temp2;
		loc(temp1, pile1, height1);
		loc(temp2, pile2, height2);
		/*loc(stoi(str2), pile1, height1);	  这种方法不可以为啥呢?
		loc(stoi(str4), pile2, height2);*/
		
		
		if (pile1 == pile2) {
			continue;
		}
		if (str == "move") {
			goback(stol(str2));
		}
		if (str3 == "onto") {
			goback(stol(str4));
		}
		move(stol(str2), stol(str4));
	}
}
int main()
{
	init();
	solve();
	print();
	return 0;
}

Answer 1

stoi当字符串不符合规范时，会抛出异常。建议使用时这样处理：

    try 
    {
        x = stoi(y);
    }

    catch (std::invalid_argument&)
    {
        // If no conversion could be performed, an invalid_argument exception is thrown.
        cout << "Invalid_argument" << endl;
    }

    catch (std::out_of_range&)
    {
        // If the value read is out of the range of representable values by an int, an out_of_range exception is thrown.
        cout << "Out of range" << endl;
    }

    catch (...) 
    {
        // everything else
        cout << "Something else" << endl;
    }