从输入文件读取并存储在数组C ++中

Question

我想从看起来像这样的file.txt中读取：

process_id运行时间

T1 23

T2 75

读取每一行并将运行时间的整数（制表符分隔）存储在数组中

我现在的问题是读取文件的内容..以及在制表符分隔后如何获取整数？

谢谢

#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;

int main () 
{
int process_id[100];
int run_time[100];  
int arrival_time[100];
char quantum[50];
int switching;

char filename[50];
ifstream ManageFile; //object to open,read,write files
cout<< "Please enter your input file";
cin.getline(filename, 50);
ManageFile.open(filename); //open file using our file object

if(! ManageFile.is_open())
{
    cout<< "File does not exist! Please enter a valid path";
    cin.getline(filename, 50);
    ManageFile.open(filename);
}

while (!ManageFile.eof()) 
{
    ManageFile>>quantum;
    cout << quantum;

}

//ManageFile.close();
return 0;
}

Answer 1

1. 使用C ++，而不是C
2. 不要使用std :: cin.getline，请使用std :: getline（它与std :: string一起使用并且更安全）
3. 使用向量而不是硬维数组
4. 使用结构的向量而不是“对应的数组”
5. 不要使用while (!stream.eof())

以下示例可能会有所帮助：

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <string>

using namespace std;

struct Record {
    int process_id;
    int run_time;
    int arrival_time;
};

int main() {
    std::vector<Record> records;

    int switching;

    std::string filename;
    ifstream infile;

    while (!infile.is_open()) {
        cout << "Please enter your input file: ";
        std::getline(std::cin, filename);
        infile.open(filename); // open file using our file object

        cout << "File cannot be opened.\n";
    }

    std::string quantum;
    std::getline (infile, quantum); // skip header row

    while (std::getline(infile, quantum)) {
        // e.g.
        Record current;
        std::istringstream iss(quantum);
        if (iss >> current.process_id >> current.run_time >> current.arrival_time)
            records.push_back(current);
        else
            std::cout << "Invalid line ignored: '" << quantum << "'\n";
    }
}

Answer 2

从istream使用功能ignore [ http://www.cplusplus.com/reference/istream/istream/ignore/]

 while (!ManageFile.eof()) { std::string process_id; int run_time; ManageFile >> process_id; ManageFile.ignore (256, '\\t'); ManageFile >> run_time; } 

Answer 3

您可以尝试如下操作：

while (!ManageFile.eof())
{
    quantum[0] = 0;
    ManageFile>>quantum;
    if (strcmp(quantum, "0") == 0 || atoi(quantum) != 0)
        cout << quantum << endl;
}

当然，你需要包括在内

Answer 4

使用fscanf代替ifstream可以使工作轻松ifstream 。

char str[100];
int n;
....
fscanf(FILE * stream,"%s %d", str, &n);

您将在str获得字符串，在n中获得整数。