User Input Strings (getline)

User Input Strings (getline)

Reading a whole sentence takes more than cin >>. Learn when each tool is right.

cin >> reads one word

string name;
cin >> name;

If the user types Ada Lovelace, only Ada lands in name. Extraction stops at the first whitespace.

getline reads a full line

#include <string>

string sentence;
getline(cin, sentence);

std::getline(cin, sentence) reads everything up to the newline, spaces included. Perfect for full sentences.

The mixing gotcha

int age;
string name;
cout << "Age: ";
cin >> age;
cout << "Name: ";
getline(cin, name);   // name is empty!

cin >> age leaves the newline behind. getline then reads that leftover newline and stops instantly, so name comes out empty.

The fix

cin >> age;
cin.ignore();        // eat the leftover newline
getline(cin, name);

Or use getline for everything and convert with stoi. Know who owns the newline and you will be fine.

TL;DR

• cin >> reads one whitespace-separated word.
• getline(cin, s) reads a full line including spaces.
• Mixing cin >> then getline leaves a stray newline.
• Use cin.ignore() to discard it.