c ++ linux ifstream读取csv文件 [英] c++ linux ifstream read csv file
问题描述
void Lexicon::buildMapFromFile(string filename ) //map
{
ifstream file;
file.open(filename.c_str() );
string wow, mem, key;
unsigned int x = 0;
while(true) {
getline(file, wow);
if (file.fail()) break; //check for error
while (x < wow.length() ) {
if (wow[x] == ',') {
key = mem;
mem.clear();
x++; //step over ','
} else
mem += wow[x++];
}
list_map0.put(key, mem); //char to string
list_map1.put(mem, key); //string to char
mem.clear(); //reset memory
x = 0;//reset index
}
file.close();
}
此函数读取2列csv文件,并创建column2的映射column1作为键。我编译g ++和文件是在大学文件共享,当我运行程序与./foo的csv文件[在同一目录文件夹中的foo]没有读...为什么?
This function reads a 2-column csv file and creates a map of column2 with column1 as the key. I compiled with g++ and the file is on the university file share, when I run the program with ./foo the csv files [in the same directory folder as foo] are not read... why?
推荐答案
也许你没有该文件的读取权限。发出命令 ls -l< csv_file>
查看您是否有权限读取。有关文件权限的详细信息,请参阅此链接 https://help.ubuntu.com/community/FilePermissions
Perhaps you don't have read permission from that file. Issue the command ls -l <csv_file>
see if you have right to read from. For more information on file permissions refer to this link https://help.ubuntu.com/community/FilePermissions
尝试以下代码适合我。
#include <iostream>
#include <stdio.h>
#include <map>
#include <string>
#include <fstream>
using namespace std;
int main(void ) //map
{
map<string, string> list_map0;
map<string, string> list_map1;
string filename = "csv";
ifstream file;
file.open(filename.c_str() );
string wow, mem, key;
unsigned int x = 0;
while(true) {
getline(file, wow);
if (file.fail()) break; //check for error
while (x < wow.length() ) {
if (wow[x] == ',') {
key = mem;
mem.clear();
x++; //step over ','
} else
mem += wow[x++];
}
list_map0[key] = mem; //char to string
list_map1[mem] = key; //string to char
mem.clear(); //reset memory
x = 0;//reset index
}
printf("%d\n", list_map0.size());
file.close();
}
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