reading from istringstream using getline and maybe strtok somehow? - c++

Question

I want to read data from stream, which has specific format, such as:
"number:name_that_can_contain_spaces:string,string,string..." without quotes where ... means that I dont know how many strings are there separated with commas and strings can have spaces before and after it but not in the middle of string, I want to stop reading at new line
I only come up with using getline() and store each line into string, but I dont know how to continue, if there is something like strtok(line, ":",":",",","\n") which would parse it for me or I have to parse it myself character by character
example of valid line format is:
54485965:abc abc abc: some string, next string , third string\n
parsed result would be:
int 54485965
string "abc abc abc"
string "some string"
string "next string"
string "third string"

Answer 1

You can read line with std::getline and then split it with std::string::find and std::string::substr. In the code below we read line from file data, then find : (so everything before it becomes number which we parse into int with std::stoi) and throw away first part. Similar we do it with name. And in the end we fill std::list with strings separated by ,.
#include <iostream>
#include <fstream>
#include <string>
#include <list>
#include <exception>
#include <stdexcept>
struct entry {
std::string name;
int number;
std::list<std::string> others;
};
int main(int argc, char** argv) {
std::ifstream input("data");
std::list<entry> list;
std::string line;
while(std::getline(input, line)) {
entry e;
std::string::size_type i = 0;
/* get number from line */
i = line.find(":");
if(i != std::string::npos) {
e.number = stoi(line.substr(0, i));
line = line.substr(i + 1);
} else {
throw std::runtime_error("error reading file");
}
/* get name from line */
i = line.find(":");
if(i != std::string::npos) {
e.name = line.substr(0, i);
line = line.substr(i + 1);
} else {
throw std::runtime_error("error reading file");
}
/* get other strings */
do {
i = line.find(",");
e.others.push_back(line.substr(0, i));
line = line.substr(i + 1);
} while(i != std::string::npos);
list.push_back(e);
}
/* output data */
for(entry& e : list) {
std::cout << "name: " << e.name << std::endl;
std::cout << "number: " << e.number << std::endl;
std::cout << "others: ";
for(std::string& s : e.others) {
std::cout << s << ",";
}
std::cout << std::endl;
}
return 0;
}