C ++向量访问错误 [英] c++ vector bad access

问题描述

我有以下c ++程序:

Hi I have the following c++ program:

#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>
#include <boost/foreach.hpp>
#include <stdexcept>
#include <boost/flyweight.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/filesystem.hpp>

namespace fs = boost::filesystem;

struct entry
{
int file;
std::vector<double> a;
};


void my_file(const std::string&file, std::vector<entry> &data, int i){
try{
    std::ifstream in(file.c_str());
    entry e;
    std::string line;
    e.file = i;
    while(getline(in,line)){
        try{
            data[i].a.push_back( boost::lexical_cast<double> (line));
        }catch(boost::bad_lexical_cast bad){
            //std::cerr << bad.what() << std::endl;
        }
    }
}catch(std::runtime_error err){
    std::cerr << err.what() << std::endl;
}

}

void write_file(const std::string &file,std::vector<entry> data,const char* t_path){
try{
    std::string new_file = t_path ;
    new_file = new_file + "/" + file;
    std::ofstream f(new_file.c_str());

    for(size_t i = 0 ;i < data[1].a.size();i++){
        std::cout << "i: " << i;
        for(size_t j = 1; j < data.size();j++){
            std::cout << "j: " << j << std::endl;
            f << data[j].a[i]<< "\t";
        }
        f << "\n";
    }

}catch(std::runtime_error err){
    std::cerr << err.what()<< std::endl;
}
}


int collect_peak(const char*argv,const char*out){
std::cout << "collecting peaks\n";
std::stringstream sstr(argv);
std::string _line;
int c = 0;
std::vector<std::string> files;

while (getline(sstr,_line)){
    std::cout << _line << std::endl;
    fs::path p(_line);
    std::string tmp = p.parent_path().string() +"/_peak_" +      p.filename().string();
    files.push_back(tmp);
    c++;
}

std::cout << "c: " << c << std::endl;
std::vector<entry> data;
for (int i=0 ; i < files.size() ;++i){
    std::cout << files[i] <<std::endl;
    my_file(files[i],data,i);
}
write_file("__peak.txt",data,out);
return 0;

}

以某种方式，它总是使我无法访问my_file方法.该程序实际上应满足以下条件:

Somehow it always gives me a bad access in the my_file method. The program should actually to the following:

1. 读取多个包含标题和十个由换行符分隔的双打的文件

2. 将所有内容输出到一个文件中，因此看起来像这样:

1. read multiple files that contain a caption and ten doubles seperated by a newline

2. output everything into one file so it looks like this:

1. 文件\ t 2.文件\ t 3.文件\ t ...

1. file \t 2. file \t 3. file \t ...

文件\ t 2.文件\ t 3.文件\ t ...

file \t 2. file \t 3. file \t ...

文件\ t 2.文件\ t 3.文件\ t ...

file \t 2. file \t 3. file \t ...

文件\ t 2.文件\ t 3.文件\ t ...

file \t 2. file \t 3. file \t ...

文件\ t 2.文件\ t 3.文件\ t ...

file \t 2. file \t 3. file \t ...

这实际上已经起作用了，但是我现在在另一个程序中重用了它.有什么想法吗?

This actually worked already, but i reused it now in a different program. Any ideas?

谢谢

推荐答案

此行:

std::vector<entry> data;

创建一个空向量，将其传递给my_file并在其中访问data[i].您需要为元素保留空间，然后才能访问向量中的任意索引.例如:

creates an empty vector, which you are passing to my_file and accessing data[i] within. You need to reserve space for the elements before you can access arbitrary indices in the vector. For example:

std::vector<entry> data(maxItems);

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