How can I access a character in the middle of a line in c++? -

i working on project consists of reading input file called input.txt has infinite number of lines. each line has roman numeral, space, plus or minus, space, , roman numeral. supposed add 2 numbers , write answer file called output.txt. however, can't think of way access operator. here sample input file:

xv + vii  xii + viii 

can give me idea of how can access plus sign each line of code?

if you're reading file standard input, can whitespace delimited tokens using extraction operator.

#include <string> #include <iostream>  int main(int argc, char *argv[]) {     std::string token;     while (std::cin >> token) {       // parse tokens here ...        // example, i'll print out stream of tokens.       std::cout << token << std::endl;     } } 

if you'd assume have 3 tokens per line, can this:

#include <string> #include <iostream>  int main(int argc, char *argv[]) {     std::string first, middle, last;     while (std::cin >> first >> middle >> last) {       // should print out operator       std::cout << middle << std::endl;     } }