Beginner's C++ program for a class - c++

Question

the assignment is the basic "cin a full name" and then "retrieve First Middle Last" bit, where you create a program that asks the user to type in their full first name into a single string and the programs picks apart the name and outputs it organized seperately. this is what i wrote:
#include <iostream>
#include <string>
using namespace std;
int main()
{
string name;
int index;
index = name.find(' ');
cin >> name;
cout << "First name: " << name.substr(0, index) << endl;
name = name.substr(index+1, name.length()-1);
index = name.find(' ');
cout << "Middle Name: " << name.substr(1, index) << endl;
name = name.substr(index+1, name.length()-1);
cout << "Last name: " << name;
return 0;
}
the code just wont seperate them right, and will not redefine 'name' correctly.
It always just bounces back to the beginning of the string.
any help for a newbie?
here's an example output:
Teenage Wonder Land
First name: Teenage
Middle Name: eenag
Last name: Teena
Process returned 0 (0x0) execution time : 7.942 s
Press any key to continue.

Answer 1

You wont' find anything before type your in console and sbustr should read from index 0
string name;
int index;
//index = name.find(' '); // comment out, name is empty, you won't find anything
cin >> name;
index = name.find(' '); // now you can find first space
cout << "Middle Name: " << name.substr(0, index) << endl;
// ^
Or just use std::stringstream
#include <sstream>
std::stringstream ss(name);
std::string token;
int i = 0;
while(ss >> token)
{
switch(i)
{
case 0:
std::cout << "First name: " << token << std::endl;
break;
case 1:
std::cout << "Middle name: " << token << std::endl;
break;
case 2:
std::cout << "Last name: " << token << std::endl;
break;
default:
break;
i++;
}
}

Answer 2

You clearly can't search for something in name before you assign it a value, which is what you're doing now:
string name;
int index;
index = name.find(' '); // No value assigned to name yet - nothing to search
cin >> name; // Now you're giving it a value (too late)
Instead, assign and then try to find a value:
string name;
int index;
cin >> name; // Assign a value first
index = name.find(' '); // Now try to find something in it

Answer 3

I think you should use std::getline to get the entire line of text at once. Currently you are only reading in the first word (>> operator will only extract text up to the next whitespace character).
std::string name;
if (std::getline(cin, name))
{
// extraction successful, "name" should contain entire line
}
Then, you can use one of the other answers in this question or continue with your own approach.

Answer 4

The extraction operator >> for istream will grab all non-whitespace characters in the buffer until it encounters a whispace.
So your input here:
Teenage Wonder Land
contains 3 whitespaces including the invisible newline at the end when you hit enter. From this you should be able to figure out what the following does:
cin >> name;
Hint: name doesn't contain the entire line you just entered.

Answer 5

#include <iostream>
#include <string>
using namespace std;
string getnext(const string &full, const string &delim, size_t &beg) {
size_t prev = beg;
beg = full.find(delim, beg);
if (beg != string::npos)
return full.substr(prev, beg-prev);
return full.substr(prev, full.length()-prev);
}
int main()
{
string name, temp, error = "NameError: Enter first, middle, last";
size_t index = 0;
getline(cin, name); //Get the full name
temp = getnext(name, " ", index); //Get first name
if (index == string::npos) {
cout << error;
return -1;
}
cout << "First name: " << temp << endl;
temp = getnext(name, " ", ++index); //Get middle name
if (index == string::npos) {
cout << error;
return -1;
}
cout << "Middle Name: " << temp << endl;
temp = getnext(name, " ", ++index); //Get last name
cout << "Last name: " << temp << endl;
return 0;
}