ifstream get line change output from char to string

Question

C++ ifstream get line change getline output from char to string

I got a text file.. so i read it and i do something like

char data[50];
readFile.open(filename.c_str());

while(readFile.good())
{
readFile.getline(data,50,',');

cout << data << endl;

}

My question is instead of creating a char with size 50 by the variable name data, can i get the getline to a string instead something like

string myData;
readFile.getline(myData,',');

My text file is something like this

Line2D, [3,2] Line3D, [7,2,3]

I tried and the compiler say..

no matching function for getline(std::string&,char)

so is it possible to still break by delimiter, assign value to a string instead of a char.

Updates:

Using

while (std::getline(readFile, line))
{
    std::cout << line << std::endl;
}

IT read line by line, but i wanna break the string into several delimiter, originally if using char i will specify the delimiter as the 3rd element which is

readFile.getline(data,50,',');

how do i do with string if i break /explode with delimiter comma , the one above. in line by line

@billz yes it say no mention function for getline(std::string&,char) — user1777711
– user1777711, Commented Nov 13, 2012 at 9:36

hmjd · Accepted Answer · 2012-11-13 09:41:57Z

6

Use std::getline():

std::string line;
while (std::getline(readFile, line, ','))
{
    std::cout << line << std::endl;
}

Always check the result of read operations immediately otherwise the code will attempt to process the result of a failed read, as is the case with the posted code.

Though it is possible to specify a different delimiter in getline() it could mistakenly process two invalid lines as a single valid line. Recommend retrieving each line in full and then split the line. A useful utility for splitting lines is boost::split().

edited Nov 13, 2012 at 9:41

answered Nov 13, 2012 at 9:35

hmjd

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3 Comments

john Over a year ago

@mhjd, good answer but maybe you could also say something about why the OP code while(readFile.good()) is wrong

user1777711 Over a year ago

@hmjd , now i get it line by line, but if i want to break it by delimiter , with the value is stored in string, how do i proceed

john Over a year ago

@user1777711 I think the best way is to get it line by line. Once you have one line you have to write string parsing code to break it up how you want to break it up. There's no quick way to do this, you just have to write the code.

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