Reading string and integers

Question

What I want to do is read a line from a text file containing a two-word string that is & lt; = 20 and two integers, for example, might look something like this:

Name Surname 1 14 

I know that if I read a line, the line will contain all characters before the space, however getline () reads the entire line as a line. So how do I read such a line? Is there an easy way, or will I have to use regular expressions?

Answer 1

May be...

 #include <iostream> #include <fstream> #include <string> using namespace std; int main() { ifstream file( "/home/facu/text.txt", ios::in ); string part1, part2; int num1, num2; if( !file ) cerr << "Cant open " << endl; while( file >> part1 >> part2 >> num1 >> num2 ) { cout << part1 << " " << part2 << " " << num1 << " " << num2 << endl; } file.close(); return 0; } 

Where text.txt:

 JONES JONES 12 14 MICHAEL MICHAEL 12 100 DOE DOE 15 20 

Answer 2

std::getline() is probably the best function for this. Then create some form of parser that limits each field to a space. From there, you can use std::stringstream to convert the fields (in this case 2 and 3, if they start at 0), to integer values. Obviously, you will want to do some error handling for any I / O operation.

EDIT: Here is an example that will help me get started

 // Example #include <iostream> #include <sstream> #include <string> #include <fstream> #define FIELD_SIZE 4 // How many fields per line // This is just a custom data structure to hold the data you want struct myInfo { myInfo(){} // Default ctor myInfo(std::string name1,std::string name2,int n1,int n2) // Ctor accepting all data : first(name1), last(name2), num1(n1), num2(n2) {} std::string first, last; int num1,num2; }; // Get the initial size of what your array should be // This is based on how many '\n are found int getNumLines(const std::string& input) { int retval = 0; for(unsigned int i=0;i<input.length();++i) if(input[i] == '\n') retval++; return retval; } // Convert string to int int convertStringToInt(const std::string& input) { std::stringstream ss(input); int retval; ss >> retval; return retval; } // Parse input and store it in our structure // Not really efficient if you have large datasets to work with void parseAndStore(std::string input, myInfo *& myArray, int size) { size_t pos = 0, pos2 = 0; // Temporary position holder std::string first, last, tmp1, tmp2; std::stringstream tmp; int num1, num2; // This is not efficient - it merely an example for(int i=0;i<size;++i) // How many items to insert for(int j=0;j<FIELD_SIZE;++j) // How many fields { if(j < FIELD_SIZE-1) { pos2 = input.find(" ",pos+1); if(pos2 == std::string::npos || pos2 > input.find('\n',pos)) // Don't run over the next line { pos = input.find('\n',pos); // Next line break; // Error - invalid line format } // Relatively hacky, but this is just an example to give you an idea switch(j) { case 1: last = input.substr(pos,pos2-pos); break; case 2: tmp1 = input.substr(pos,pos2-pos); break; default: first = input.substr(pos,pos2-pos); break; } pos = pos2+1; } else { // All data collected - parse our ints and store it in our structure pos2 = input.find('\n',pos); // End of line tmp2 = input.substr(pos,pos2); // Convert num1 = convertStringToInt(tmp1); num2 = convertStringToInt(tmp2); // Insert it into our array myArray[i] = myInfo(first,last,num1,num2); pos = pos2+1; // Advance position } } } int main() { // Read your input file - this is just an example std::string input("Joe Serma 1 30\nGeorge Hola 2 17\n"); int size = getNumLines(input); // Parse the number of lines in your input myInfo * myArray = new myInfo[size]; // Allocate a dynamic array to store your data parseAndStore(input,myArray,size); // Parse this string - leave the original in tact though // Print contents of the array for(int i=0;i<size;++i) { std::cout<< std::endl << "=== Person "<< i+1 << "===" << std::endl << "First: "<< myArray[i].first << std::endl << "Last: "<< myArray[i].last << std::endl << "Num1: "<< myArray[i].num1 << std::endl << "Num2: "<< myArray[i].num2 << std::endl << "Num1+Num2 (For confidence of true int): "<< myArray[i].num1+myArray[i].num2 << std::endl; } delete [] myArray; // Cleanup return 0; } 

Yours faithfully,
Dennis M.