trying to read and store data from a file where there are multiple spaces between each intended data - c++

Question

Here's a simple code on how I read and store the data. I have a text file and inside the text file are the data that I want to pass to both number and text. The code runs fine if the text file contains text such as 2 HelloWorld1, 2 is stored into number and HelloWorld1 is stored into text.
But what if the text in the txt file is as such, 2 Hello World 1 where there are spaces between Hello, World and 1? My question is would it be possible for 2 to be stored in number and Hello World 1 to be stored in text. i understand that because of the empty spaces and as such only 2 and Hello and stored in both number and text respectively. Is there a way to overcome this?
using namespace std;
int main(){
ifstream theFile("key.txt");
int number;
string text;
while(theFile>>number>>text){
cout<<number<<" and "<<text<<endl;
}
}

Answer 1

You are out of luck with the default stream operator >> (if that is indeed your case).
1: Know the format
The way forward is to know the format which judging from your post you are somewhat uncertain about.
2: Use the best tools for the job
After that you choose the right tool for the job. That could involve: std::getline and handpassing, perhaps using a regex (in your case, fairly simply ones), boost::spirit, tokenization techniques, boost::string_algo, lex/bison and more.
I would add that customizing stream operator functionality (while possible) is rarely the straightforward choice.
3: Design your format to match
As an alternative to knowing the format, if you can design it, so much the better. If you have record style format, an easy way to handle strings with spaces is to put the string last - then put each record on a line. That way you may first look over each line using eg. std::getline and then just use stream operators for the rest - knowing the string will come last. Other delimiters (than linefeed) is certainly doable as well.

Answer 2

I would like to add an example to the very good answer of #darune.
It all depends on the input format.
Assuming that your line starts with a number and then ends with a string, you can use the following approach:
First read a number with extractor operator >>
Use getline to read the rest
Please see:
#include <iostream>
#include <string>
#include <sstream>
#include <cctype>
#include <algorithm>
#include <regex>
std::istringstream testData (
R"#(1 data1
2 data2 data3
3 data 4
)#");
int main()
{
// Definition of variables
int number{};
std::string str{};
// Read file
// Read the number
while (testData >> number)
{
// Read the rest of the line in a string
getline(testData, str);
// Remove leading and trailing spaces
str = std::regex_replace(str, std::regex("^ +| +$|( ) +"), "$1");
// Show result
std::cout << number << ' ' <<str << '\n';
};
return 0;
}
Result:
1 data1
2 data2 data3
3 data 4
But as said, it strongly depends on the input format