我目前正在尝试将文本文件加载到结构数据成员中。每个数字用逗号分隔。
#include<string>
#include<sstream>
using namespace std;
struct server{
bool isBusy;
};
struct pass{
double arrivalTime = 0;
double serviceTime = 0;
int classType = 0;
};
int main(){
string fileName;
string line;
pass Pass;
cout << "Enter file name: ";
cin >> fileName;
ifstream fin(fileName);
while (getline(fin, line, ','))
{
/*NEED HELP HERE*/
fin >> Pass[0].arrivalTime;
fin >> Pass[0].serviceTime;
fin >> Pass[0].classType;
}
}
下面是一个文本文件的示例。
0.951412936,2.131445423,0
1.902743503,2.010703852,0
2.537819984,2.326199911,0
3.425838997,1.603712153,0
3.502553324,0.998192867,0
3.917348666,1.49223429,0
4.391605986,0.831661367,0
4.947059678,0.8557003,0
5.429305232,2.42029408,0
文本文件中的数据遵循以下格式：
arrivalTime，serviceTime，classType
正如你所看到的，我已经将行拆分并使用逗号分隔符将其存储在"行"中，但我不确定如何在while循环中将每个数字加载到结构中。
如有任何帮助，我们将不胜感激。
为结构定义istream operator >>。类似的东西
struct pass {
double arrivalTime = 0;
double serviceTime = 0;
int classType = 0;
friend std::istream & operator >>(std::istream & in, pass & p) {
char c;
in >> p.arrivalTime >> c >> p.serviceTime >> c >> p.classType;
return in;
}
};
然后，简单的
pass Pass;
fin >> Pass;
while (getline(fin, line))
{
sscanf(line.c_str(), "%lf,%lf,%d", &arrivalTime, &serviceTime, &classType);
}
此循环错误：
while (getline(fin, line, ','))
{
/*NEED HELP HERE*/
fin >> Pass[0].arrivalTime;
fin >> Pass[0].serviceTime;
fin >> Pass[0].classType;
}
您正在读取从流到下一个','字符的所有内容，然后尝试从流中读取更多内容。
给定输入文件：
0.951412936,2.131445423,0
1.902743503,2.010703852,0
2.537819984,2.326199911,0
您的程序将"0.951412936"读入line(并丢弃','(，然后尝试将下一个输入读入Pass[0].arrivalTime，但下一个输出是2.131445423，即serviceTime(您已将其读入line(。
正如Shreevardhan所建议的，您可以定义一个运算符来从流中读取结构。我会让它更可靠：
struct ExpectedChar { char expected; };
// read a character from a stream and check it has the expected value
std::istream& operator>>(std::istream& in, const ExpectedChar& e)
{
char c;
if (in >> c)
if (c != e.expected) // failed to read expected character
in.setstate(std::ios::failbit);
return in;
}
// read a struct pass from a stream
std::istream& operator>>(std::istream& in, pass& p)
{
ExpectedChar comma{ ',' };
in >> p.arrivalTime >> comma >> p.serviceTime >> comma >> p.classType;
return in;
}
如果输入文件不符合预期格式，这将停止读取。现在你可以做：
while (fin >> Pass)
{
// do something with each pass
}
if (!fin.eof()) // stopped reading before end-of-file
throw std::runtime_error("Invalid data in input file");
这将继续从文件中读取pass，直到读取失败，可能是因为它到达了文件的末尾，也可能是因为文件中有一些坏数据。如果有坏数据，它会抛出一个异常。
#include<string>
#include<iostream>
#include<fstream>
#include<vector>
using namespace std;
struct server{
bool isBusy;
};
struct pass{
double arrivalTime;
double serviceTime;
int classType;
friend std::istream & operator >>(std::istream &in, pass &p) {
char c;
in >> p.arrivalTime >> c >> p.serviceTime >> c >> p.classType;
return in;
}
};
int main(){
string fileName;
string line;
cout << "Enter file name: ";
cin >> fileName;
ifstream fin(fileName.c_str(), ifstream::in);
vector<pass> passes;
pass Pass;
while (fin>>Pass)
passes.push_back(Pass);
for(vector<pass>::const_iterator iter = passes.begin();
iter != passes.end();
++iter)
std::cout<<iter->arrivalTime<<" "<<iter->serviceTime<<" "
<<iter->classType<<std::endl;
}
这里有提示；
string line;
string temp;
string::size_type sz;
while (getline(cin, line))
{
istringstream ss( line );
getline( ss, temp, ',' );
double arrivalTime = stod(temp, &sz);
getline( ss, temp, ',' );
double serviceTime = stod(temp, &sz);
getline( ss, temp, ',' );
double classType = stod(temp, &sz);
cout << arrivalTime << ' '
<< serviceTime << ' '
<< classType << endl;
}