[英]C++ Read String from Text file and save word by word into linkedlist
我被分配编写一个用于房间预订系统的C ++程序。 我知道如何逐行读取文本文件并将其保存。 但是我的问题是如何逐字读取文本文件。
这是我拥有的文本文件:
1-Reserved-2018-12-23-Lecture Room-13
2-Reserved-2018-11-34-Tutorial Room-15
3-Not Reserved-0-0-0-Design Studio-18
4-Reserved-2018-11-16-Lecture Room-14
5-Not Reserved-0-0-0-Exam Hall-18
我想读取文本文件并将单词保存到节点中。 (例如ID
, data
, typeofRoom
等。)在C ++中有什么方法可以这样做?
这是我的课:
class room {
public:
int length;
int initial;
enum class roomType { main_hall, exam_hall, lecture_room, tutorial_room, design_studio, meeting_room };
struct node {
string data;
int id;
int capacity;
int year, month, day;
int deleteDate;
roomType type;
node* next;
};
node* front;
node * tail;
room() {
length=0;
initial=1;
front = NULL;
tail = NULL;
}
bool isFull () { return length>=20; }
// Add Rooms
void room::addRoom() {
system("cls");
if (isFull()) {
cout<<" No more than 25 rooms are allowed\n"<<endl;
return;
}
cout << "Enter the capacity" << endl;
int a;
cin >> a;
node* temp = new node();
temp->data = "Not Reserved";
temp->id = initial;
temp->year = 0;
temp->month = 0;
temp->day = 0;
temp->deleteDate = 0;
initial++;
temp->capacity = a;
temp->next = NULL;
if (front == NULL && tail == NULL)
{
front = temp;
tail = temp;
}
else {
tail->next = temp;
tail = temp;
}
cout << "Choose The type" << endl;
cout << "1- Main Hall \t 2- Lecture Room \t 3- Exam Hall \t 4- Meeting Room \t 5- Design Studio \t 6- Tutorial Room" << endl;
int t;
cin >> t;
if (t == 1)
{
temp->type = roomType::main_hall;
}
else if (t == 2)
{
temp->type = roomType::lecture_room;
}
else if (t == 3)
{
temp->type = roomType::exam_hall;
}
else if (t == 4)
{
temp->type = roomType::meeting_room;
}
else if (t == 5)
{
temp->type = roomType::design_studio;
}
else if (t == 6)
{
temp->type = roomType::tutorial_room;
}
else {cout << "Wrong Input!" << endl;}
length++;
cout<<"\n Successfully Created!\n\n";
system("pause");
save();
}
void reserveRoom()
{
system("cls");
show();
cout << "=============================================================" << endl;
cout << "Enter the room ID you want to Book !" << endl;
int id;
cin >> id;
node* tmp = front;
while (tmp != NULL) {
if (tmp->id == id) {
if(tmp->data == "Not Reserved"){
tmp->data = "Reserved";
int y,m,d;
cout << "Enter the year " << endl;
cin >> y;
cout << "Enter the month " << endl;
cin >> m;
cout << "Enter the day " << endl;
cin >> d;
tmp->year = y;
tmp->month = m;
tmp->day = d;
tmp->deleteDate = y+m+d;
cout << "Room Reserved!" << endl;
}
else{
cout << "This room has been reserved!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!" << endl;
}
}
tmp = tmp->next;
}
system("pause");
room::save();
}
};
我知道如何逐行读取文本文件并将其保存。 但是我的问题是如何逐字读取文本文件。
这是我拥有的文本文件:
1-Reserved-2018-12-23-Lecture Room-13 2-Reserved-2018-11-34-Tutorial Room-15 3-Not Reserved-0-0-0-Design Studio-18 4-Reserved-2018-11-16-Lecture Room-14 5-Not Reserved-0-0-0-Exam Hall-18
继续我上面的评论,每当您遇到将单词分隔成一行并在单词之间使用分隔符的情况时,一种标准的方法是将每一行都用getline
组成一个string
,然后从该行创建一个stringstream
,将每个单词读为一个string
将getline
与指定的分隔符一起使用。
为什么要阅读与线getline
和阅读stringstream
与getline
一遍吗?
答:线路控制。
虽然您可以简单地使用getline
和分隔符直接读取文件,分隔符将每个单词分开,但是您如何知道一行结束和下一行开始的时间呢? 当您指定与getline
一起使用的定界符时, getline
会一直读取,直到找到定界符或已读完输入或str.max_size
字符str.max_size
。 参见cppreference.com-std :: getline 。 因此,在这种情况下,行尾'\\n'
没有特殊含义。
但是,如果你读了整条生产线成string
,然后创建一个stringstream
从行,你知道你只能读,直到最后的行为,将触发输入端的文件状态。 因此,即使您使用带有分隔符的getline
,它现在也只能读取到行尾。
一个使用此方法并使用数据文件的简短示例将说明如何将每一行分成单词,然后将其添加到列表的每个节点,例如
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
int main (int argc, char **argv) {
std::string line; /* string to hold each line */
if (argc < 2) { /* validate at least 1 argument given */
std::cerr << "error: insufficient input.\n"
"usage: " << argv[0] << " filename\n";
return 1;
}
std::ifstream f (argv[1]); /* open file */
if (!f.is_open()) { /* validate file open for reading */
perror (("error opening file " + std::string(argv[1])).c_str());
return 1;
}
while (getline (f, line)) { /* read each line into line */
std::string word; /* string to hold words */
std::stringstream s (line); /* create stringstream from line */
while (getline (s, word, '-')) /* read hyphen separated words */
std::cout << word << '\n'; /* output words */
std::cout << '\n'; /* tidy up with newline between data */
}
}
输入文件示例
$ cat ../dat/hyphenstr.txt
1-Reserved-2018-12-23-Lecture Room-13
2-Reserved-2018-11-34-Tutorial Room-15
3-Not Reserved-0-0-0-Design Studio-18
4-Reserved-2018-11-16-Lecture Room-14
5-Not Reserved-0-0-0-Exam Hall-18
使用/输出示例
注意,上面的代码只是在与每行分隔的单词之间简单地输出一个附加的'\\n'
。 您将编写逻辑(也许使用计数器,例如,进行任何需要的转换为stoi
)以将值转换为整数值并将每个值存储在其适当的字段中。
$ ./bin/getline_hyphen ../dat/hyphenstr.txt
1
Reserved
2018
12
23
Lecture Room
13
2
Reserved
2018
11
34
Tutorial Room
15
3
Not Reserved
0
0
0
Design Studio
18
4
Reserved
2018
11
16
Lecture Room
14
5
Not Reserved
0
0
0
Exam Hall
18
您还可以从每一行中删除分隔符,创建一个不带连字符的单独stringstream
,并使用>>
读取和转换每个节点的值。 (第二种方法留给您)
仔细检查一下,如果您还有其他问题,请告诉我。
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