Parsing coordinates from file using c++ - c++

Question

I have a question about parsing coordinates from a file into my C++ program.
The content of the file "file.txt" consists of one line: "1,2"
the 1 needs to be the X coordinate. The ',' is the delimiter. And the 2 is the Y coordinate.
The output of my program is: "1".
It looks like my program only puts the string in front of the delimiter in the vector and then thinks its the end of the file.
How can i solve this problem?
You can find my code down here. Thanks in advance!
#include <string>
#include <vector>
#include <fstream>
#include <iostream>
#include <sstream>
char data[220];
void parseString(std::string string);
int main(int argc, char **argv) {
std::ifstream indata("file.txt");
std::vector <std::string> buffer(5);
int i = 0;
while(indata.good())
{
indata.getline(data, 220);
parseString(data);
++i;
}
return 0;
}
void parseString(std::string string){
std::string delimiter = ",";
size_t pos = 0;
std::string token;
std::vector<std::string> tempVector(2);
int i = 0;
while ((pos = string.find(delimiter)) != std::string::npos) {
token = string.substr(0, pos);
tempVector[i] = token;
string.erase(0, pos + delimiter.length());
}
for(std::string S : tempVector){
std::cout << S << std::endl;
}
}

Answer 1

Here is the problem come from:
while ((pos = string.find(delimiter)) != std::string::npos) {
token = string.substr(0, pos);
tempVector[i] = token;
string.erase(0, pos + delimiter.length());
}
After the first loop parsing (in while), you erase the first part, i.e. "1,", which leaves you only "2". Then you will stop here as no more delimiter is in it. That's why you only got 1.
You can simply put string data into a std::istringstream, then you can parse data easily by using >>:
std::istringstream iss(data); // e.g. data = "1,2"
int first_int, second_int;
char delimiter;
iss >> first_int >> delimiter >> second_int;
| | |
1 ',' 2

Answer 2

The root of the problem is that your requirements are underspecified. For example:
Can you assume that every coordinate is just from 0 to 9? Or are there coordinates with more digits?
Can there be negative coordinates? Should you be able to handle a minus character? Is a plus character allowed, i.e. something like "-1,+1"?
Where is whitespace allowed?
Do you have to handle errors such as when the file is empty or there is no ',' at all, or if there are multiple commas, or if one of the supposed numbers does not consist of digits?
Are you allowed to ignore everything after correct input, i.e. something like "1,2xxx"?
For the simplest of requirements imaginable here, you could just do:
if (data[1] == ',') {
int x = data[0] - '0';
int y = data[2] - '0';
}
But that's apparently not good enough. So you do have more complex requirements, and I think you should put more thought into them. Only then will you be able to produce a really correct program.
As a final word, mind that user input is always a very complex thing, and it's generally hard to think about and cover each and every corner case, but everyone likes programs which handle user input correctly and intuitively and report errors in the most precise way possible, don't we? :)