Using getline() with file input in C++

Question

I am trying to do a simple beginner's task in C++. I have a text file containing the line "John Smith 31". That's it. I want to read in this data using an ifstream variable. But I want to read the name "John Smith" into one string variable, and then the number "31" into a separate int variable.

I tried using the getline function, as follows:

ifstream inFile;
string name;
int age;

inFile.open("file.txt");

getline(inFile, name); 
inFile >> age; 

cout << name << endl;
cout << age << endl;  

inFile.close();    

The problem with this is that it outputs the entire line "John Smith 31". Is there a way I can tell the getline function to stop after it has gotten the name and then kind of "restart" to retrieve the number? Without manipulating the input file, that is?

Answer 1

getline , as it name states, read a whole line, or at least till a delimiter that can be specified.

So the answer is "no", getline does not match your need.

But you can do something like:

inFile >> first_name >> last_name >> age;
name = first_name + " " + last_name;

Answer 2

you should do as:

getline(name, sizeofname, '\n');
strtok(name, " ");

This will give you the "joht" in name then to get next token,

temp = strtok(NULL, " ");

temp will get "smith" in it. then you should use string concatination to append the temp at end of name. as:

strcat(name, temp);

(you may also append space first, to obtain a space in between).

Answer 3

ifstream inFile;
string name, temp;
int age;

inFile.open("file.txt");

getline(inFile, name, ' '); // use ' ' as separator, default is '\n' (newline). Now name is "John".
getline(inFile, temp, ' '); // Now temp is "Smith"
name.append(1,' ');
name += temp;
inFile >> age; 

cout << name << endl;
cout << age << endl;  

inFile.close();    

Answer 4

you can use getline from a file using this code. this code will take a whole line from the file. and then you can use a while loop to go all lines while (ins);

 ifstream ins(filename);
string s;
std::getline (ins,s);