getline

问题 Firstly, I'm pretty new to C++. I believe that getline() isn't a standard C function, so #define _GNU_SOURCE is required to use it. I'm now using C++ and g++ tells me that _GNU_SOURCE is already defined: $ g++ -Wall -Werror parser.cpp parser.cpp:1:1: error: "_GNU_SOURCE" redefined <command-line>: error: this is the location of the previous definition Can anyone confirm if this is standard, or is its definition hidden somewhere in my setup? I'm not sure of the meaning of the final line quoted.

问题 Following up https://stackoverflow.com/a/1120224/390066. Why can't I use getline(stringstream(line),cell,','){} instead of stringstream lineStream(line); getline(lineStream,cell,','){} ? update I should have clarified that I want to use getline within a loop. Furthermore, I should have also noted that my initial intention was to read a file line-by-line using getline and use the line from that in the new getline that would divide on ',', which is more intuitive imo. From what I understood so

问题 I need to write numbers and text in a text file, for an unknown reason, the writing works, the reading does not, the problem is reading the text as in the following example: fstream ff,ff2; int a,b; ff.open("simtestagain.txt",ios::out); CString mycstring = _T("Name with spaces"); char mycharbuffer[255]; //destination buffer size_t convertedChars = 0; //number of characters converted wcstombs_s( &convertedChars, mycharbuffer, mycstring.GetLength()+1,mycstring.GetBuffer(), _TRUNCATE); ff << 1 <

问题 I am trying to read a csv using get line to extract three variables separated by commas. Name, Course, and Grade. I am reading in the first line fine but it puts in weird new line breaks and sends the format into a cluster. Here is my code : #include "header.h" string student::GetCourse() { return course; } string student::GetName() { return name; } string student::GetGrade() { return grade; } void student::setname(string n) { name = n; } void student::setCourse(string c) { course = c; } void

问题 For some reason the full lines from my input file are not reading into the array, only the first word in each line. I am currently using the getline call, but I am not sure why it is not working. Here is the what I have for the call to populate the array. The txt file is a list of songs. const int numTracks = 25; string tracks[numTracks]; int count = 0, results; string track, END; cout << "Reading SetList.txt into array" << endl; ifstream inputFile; inputFile.open("SetList.txt"); while (count

问题 I have csv file input where I read in multiple lines which contain multiple fields related to that line. How do I write a loop which reads a line of text from the csv file, then keeps looping until it reaches the end of that line. This while loop would be nested in an !infile.eof while loop. Here is what I has so far but doesn't work exactly. while (getline(infile, currentline)) { getline(infile, ID, ','); getline(infile, Name, ';'); Person p = new Person(ID, Name); } A line in the csv file

问题 I am trying to write a program in C++ that emulates a college enrollment system, where the student enters their ID, and the program searches a text file for their information, and loads a struct based on the text file. I have gotten to a point where I am having trouble getting their enrolled courses into the struct's array. Using the getline function, using the ',' as the delim will also carry over the next line until the next comma. What would be the correct algorithm for this? This is the

问题 I was given a homework assignment to generate a txt file containing a random number of lines, each with a random amount of integers, ranging between a minimum value and a maximum value. Lots of rand() fun. In any case, that was the easy part. The second part of the problem is to read over the first file and create a second file that contains some statistics, such as: the sum of all integers in the file, their average, min and max values, and my main issue: the sum of all integers in each line

问题 I am able to write to a text file then I use getline and I can no longer write to the file. #include <iostream> #include <fstream> #include <string> using namespace std; int main(){ ifstream infile; fstream crypto; ofstream hacker; string tempString; string tempString2; string plaintext; string line; string dec; . . . crypto<<"hello";//write some stuff to file here use getline(crypto, line, '\n') crypto<<"hi";//Doesnt write to file anymore. 回答1: Files have a single error status and a shared

问题 in VC++ environment Im using (string) getline function to read separate lines in opened file. Problem is that getline takes character 1Ah as end of file and if it is present on the line, whole reading ends prematurely. Is there any solution for this? Code snippet: fstream LogFile (Source,fstream::in); string Line while (getline(LogFile,Line)) { .... } File contents: line1text1asdf line2text2asd //EOF for getline here line3asdas // this line will never be read by getline Thank you for any info