C++ stringstream格式化輸出輸入詳情

更新時(shí)間：2021年11月12日 09:24:32 作者：小河溝大河溝

這篇文章主要介紹了C++ stringstream格式化輸出輸入，首先string str; cin>>str;遇到空格結(jié)束；于是乎產(chǎn)生了getline(),可與得到一行字符串；空格自動(dòng)去掉，下面來看看文章的詳細(xì)內(nèi)容，需要的小伙伴可以參考一下

int main()
{

    string line;
    int k = 1;
    cout << "===============case1================" << endl;;
    while (getline(cin, line)) //可與讀到包含空格， ；等字符；但是在ss>>x時(shí)被截?cái)?
    {
        int sum = 0, x;
        stringstream ss(line);
        while (ss >> x)
        {
            sum += x;
        }
        cout << "the sum is :" << sum << endl;
        ++k;
        cout << endl;
        cout << "===============case" << k << "================" << endl;;
    }

    return 0;
}

-輸出:

===============case1================
1 2 3 4 5
the sum is :15

===============case2================
1,2,3,4,5
the sum is :1

===============case3================
1 a 2 b 3
the sum is :1

===============case4================
a 1 1 1 1
the sum is :0

===============case5================

另外一組：

int main()
{

    string line;
    int k = 1;

    cout << "===============case1================" << endl;;
    while (getline(cin, line))
    {
        string out, x;
        stringstream ss(line);
        while (ss >> x)
        {
            cout << x << ";";
        }
        ++k;
        cout << endl;
        cout << "===============case" << k << "================" << endl;;
    }

    return 0;
}

輸出：

===============case1================
this is very good!
this;is;very;good!;
===============case2================
this,is,very,good!
this,is,very,good!;
===============case3================

實(shí)驗(yàn)矩陣類型的輸入：

3

0 1 2

2 3 4

5 6 7

int main()
{

    string line;
    int k = 1;
 //測(cè)試矩陣形式的輸入：
    string input;
    int n;
    //cin >> n; //輸入n行數(shù)據(jù),如果后面用getline()后面的換行符不能處理
    getline(cin, input);
    stringstream ss(input);
    ss >> n;
    
    vector<vector<int> > vec;
    for (int i = 0; i < n;i++)
    {
        getline(cin,input); //會(huì)將換行符當(dāng)做一行
        stringstream ss(input);
        int x;

        vector<int> temp;
        while (ss>>x) //只能以空格處理分離
        {
            temp.push_back(x);
        }
        vec.push_back(temp);
    }


    return 0;
}

使用方法：

input1是沒有空格的，帶有，；將矩陣的行列分出來；
但是使用cin>>k后，沒有使用getline(input1), 應(yīng)為input1本身是沒有空格的字符串

經(jīng)上面啟發(fā)：練習(xí)這樣的輸入：

3 3
0,1 0,2;0,0 1,0;0,1 1,1;0,2 1,2;1,0 1,1;1,1 1,2;1,1 2,1;1,2 2,2;2,0 2,1

測(cè)試代碼：

int main()
{

    string line;
    int k = 1;

    int row, col;
    getline(cin, line);
    stringstream ss(line);
    ss >> row >> col;
    getline(cin, line); //第二行
    stringstream s(line);
    string temp1, temp2, temp3;;
    vector<pair<pair<int,int>,pair<int,int>>> vec;
    while (getline(s, temp1, ';'))
    {
        vector<pair<int, int>> pair1;
        stringstream s3(temp1);
        while (getline(s3, temp2,' ')) //以換行符結(jié)束，中間為空格
        {
            pair<int, int> pair2;
            stringstream s4(temp2);
            vector<int> res;
            while (getline(s4, temp3, ','))
            {
                res.push_back(stoi(temp3));
            }
            pair2.first = res[0];
            pair2.second = res[1];

            pair1.push_back(pair2);
        }

        vec.push_back(make_pair(pair1[0],pair1[1]));
    }


    return 0;
}

輸出：

另外參考輸入遇到過問題題解:

5 0
1 2 3
0 4
0 4
0 4
1 2 3

int main()
{
    int N, id;
    string str;
    getline(cin, str);
    stringstream ss(str);
    ss >> N >> id;

    vector<vector<int>> vec;
    //for (int i = 0; i < N; i++)
    //{
    //  vector<int> temp;
    //  int user;
    //  getline(cin, str);
    //  stringstream s(str);
    //  while (s>>user) //以空格進(jìn)行劃分
    //  {
    //      temp.push_back(user);
    //  }
    //  vec.push_back(temp);
    //}

    while (getline(cin, str)) //其實(shí)可都可以不知道行數(shù)
    {
        vector<int> temp;
        int user;
        stringstream s(str);
        while (s >> user)
        {
            temp.push_back(user);
        }
        vec.push_back(temp);
    }

    cout << recommendFriends(vec, id) << endl;

    return 0;
}

int test()
{
    //int N,id;
    //cin >> N >> id; //直接輸入用戶數(shù)和需要查找的用戶id ; 這樣就會(huì)產(chǎn)生換行符

    int N;
    vector<int> in;
    char c;
    while ((c = cin.get()) != '\n')
    {
        cin.unget();
        cin >> N; 
        in.push_back(N);
    }
    
    vector<vector<int>> vec;
    for (int i = 0; i < in[0]; i++)
    {
        vector<int> temp;
        int user;
        
        while ((c=cin.get())!= '\n') //文件結(jié)果沒有換行符了，所以陷入死循環(huán)
        {
            cin.unget();
            cin >> user;
            temp.push_back(user);
        }
        if (temp.size()!=0)
        {
            vec.push_back(temp);
        }
        
    }

    cout << recommendFriends(vec, in[1]) << endl;

    return 0;
}

全部代碼:

#include <iostream>
#include <algorithm>
#include <vector>
#include <unordered_map>
#include <unordered_set>

#include<sstream>
#include<fstream>
using namespace std;

#define cin infile //一定不能再oj系統(tǒng)中，有錯(cuò)，導(dǎo)致超時(shí)等?。?！
//C++文件輸入
ifstream infile("ini.txt", ifstream::in);


//函數(shù)功能：將輸入字符串s,以字符串c(;)進(jìn)行拆分,拆分結(jié)果放在v中
//函數(shù)參數(shù)說明：s為輸入字符串；c為拆分的字符串；v為拆分結(jié)果
//函數(shù)返回值：正常返回0
int split_string(const std::string& s, std::vector<std::string>& v, const std::string& c)
{
    std::string::size_type pos1, pos2;
    pos2 = s.find(c);
    pos1 = 0;
    while (std::string::npos != pos2)
    {
        v.push_back(s.substr(pos1, pos2 - pos1));

        pos1 = pos2 + c.size();
        pos2 = s.find(c, pos1);
    }
    if (pos1 != s.length())
        v.push_back(s.substr(pos1));
    return 0;
}

int main()
{

    string line;
    int k = 1;
    /*cout << "===============case1================" << endl;;
    while (getline(cin, line))
    {
        int sum = 0, x;
        stringstream ss(line);
        while (ss >> x)
        {
            sum += x;
        }
        cout << "the sum is :" << sum << endl;
        ++k;
        cout << endl;
        cout << "===============case" << k << "================" << endl;;
    }*/

    //cout << "===============case1================" << endl;;
    //while (getline(cin, line))
    //{
    //    string out, x;
    //    stringstream ss(line);
    //    while (ss >> x)
    //    {
    //        cout << x << ";";
    //    }
    //    ++k;
    //    cout << endl;
    //    cout << "===============case" << k << "================" << endl;;
    //}

    ////測(cè)試矩陣形式的輸入：
    //string input;
    //int n;
    ////cin >> n; //輸入n行數(shù)據(jù),如果后面用getline()后面的換行符不能處理
    //getline(cin, input);
    //stringstream ss(input);
    //ss >> n;
    //
    //vector<vector<int> > vec;
    //for (int i = 0; i < n;i++)
    //{
    //    getline(cin,input); //會(huì)將換行符當(dāng)做一行
    //    stringstream ss(input);
    //    int x;
    //    vector<int> temp;
    //    while (ss>>x) //只能以空格處理分離
    //    {
    //        temp.push_back(x);
    //    }
    //    vec.push_back(temp);
    //}

    int row, col;
    getline(cin, line);
    stringstream ss(line);
    ss >> row >> col;
    getline(cin, line); //第二行
    stringstream s(line);
    string temp1, temp2, temp3;;
    vector<pair<pair<int,int>,pair<int,int>>> vec;
    while (getline(s, temp1, ';'))
    {
        vector<pair<int, int>> pair1;
        stringstream s3(temp1);
        while (getline(s3, temp2)) //以換行符結(jié)束，中間為空格
        {
            pair<int, int> pair2;
            stringstream s4(temp2);
            vector<int> res;
            while (getline(s4, temp3, ','))
            {
                res.push_back(stoi(temp3));
            }
            pair2.first = res[0];
            pair2.second = res[1];

            pair1.push_back(pair2);
        }

        vec.push_back(make_pair(pair1[0],pair1[1]));
    }


    return 0;
}

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