Summary - Advanced strings
- C++ course
- Beginner
- Lesson 93/116
- 5 min
Combine stringstream, stoi and to_string to write a CSV parser.
Summary: Parse a CSV line
In this summary we will combine istringstream, stoi and to_string to parse a CSV line. CSV separates values with commas; for example, "Alex,25,90" holds a name, age and grade.
The plan is: first use getline on an istringstream to read up to the comma, then pull the remaining two values with >>. Convert numbers with stoi, and fold the result into text with to_string. This combines different string operations in a single task.
Practice Read name and age from a CSV line
Add the #include <sstream> header. Define istringstream iss("Alex,25");. Declare string name; and int age;. Read the name up to the comma with getline(iss, name, ',');; pull the remaining integer with iss >> age;. Print with cout << name << " - " << age << endl;.
Starter code
#include <iostream>
#include <string>
// add the sstream header
using namespace std;
int main() {
// define istringstream, read name with getline, pull age with >>, print
return 0;
}Sample solution
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main() {
istringstream iss("Alex,25");
string name;
int age;
getline(iss, name, ',');
iss >> age;
cout << name << " - " << age << endl;
return 0;
}Expected output
Alex - 25
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does getline(iss, name, ',') do?
- Reads the whole line into one string
- Reads from the stream up to a comma Correct answer
- Converts a number to an integer
- Inserts a piece into a string
Explanation: The third parameter is the delimiter; getline reads up to the comma.
2 Match each function with its job
| Term | Meaning |
|---|---|
istringstream |
Turns string into a stream |
getline |
Reads up to a delimiter |
stoi |
Converts to integer |
to_string |
Converts to string |
3 Fill in the blank: getline call
istringstream iss("Alex,30");
string name;
____(iss, name, ',');istringstream iss("Alex,30");
string name;
getline(iss, name, ',');Explanation: getline reads from the stream up to the comma.