Accelerated C++ Chapter 3 exercise 3.4

[Madmartigan]

Hi

I'm very new to programming and have purchased the book by Andrew Koenig and Barbara Moo. I am a tad frustrated at the moment because I cannot fiigure out the following from Q3.4 in the exercises:

-> How do I calculate the size of the strings in a vector that I've created?
-> How do I then keep the maximum and minumum of the strings the user
enters to ouput the respective longest and shortest strings?

Here is my code thus far :

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <ios>
#include <string>
#include <vector>

using std::cin; using std::sort;
using std::cout; using std::endl;
using std::string; using std::streamsize ;
using std::vector; using std::setprecisi on;

int main()
{
// ask for and read the user's name
cout << "Please enter your first name: ";
string name;
cin >> name;
cout << "Hello, " << name << "!" << endl;

// ask for and read family member's names
cout << "Please enter all your family members names, "
"followed by end-of-file: ";
vector<string> family;
string x;
// invariant:famil y contains all family names read so far
while (cin >> x)
family.push_bac k(x);

// check that the user entered some names
typedef vector<string>: :size_type vec_sz;
vec_sz size = family.size();
if (size == 0) {
cout << endl << "You must enter two or more family names. "
"Please try again." << endl;
system("PAUSE") ;
return 1;
}
// sort the names
sort(family.beg in(), family.end());

// run through the vector elements using r rows of input
int max = family[0].size();
int r = 0;
for (int r = 0; r != family.size(); ++r) {
while (cin >> x)
string::size_ty pe name_size = family[x].size();
??Aggghhh! Please help.}

system("PAUSE") ;
return 0;
}


If anyone can help I'd really really appreciate it.

Thanks

M

[Ganon11]

-> How do I calculate the size of the strings in a vector that I've created?
-> How do I then keep the maximum and minumum of the strings the user
enters to ouput the respective longest and shortest strings?

// run through the vector elements using r rows of input
int max = family[0].size(); 
int r = 0;
for (int r = 0; r != family.size(); ++r) {
while (cin >> x) 
string::size_type name_size = family[x].size();
??Aggghhh! Please help.}

The method you are using should be working - I think the problem you have is the while loop in the middle. Should you be using r to access each member of the vector? Once you get the size of a string in the vector, you can compare it to the value you have in max (and a min value) to update the size - or even better, the position of the string with the longest/shortest length.

int max = 0;
int min = 0;
for (int r = 1; r < family.size(); r++) {
if (family[r].length() > family[max].length()) max = r;
if (family[r].length() < family[min].length()) min = r;
}
// max holds the position of the longest string in family
// min holds the position of the shortest string in family

[Madmartigan]

Thanks for the reply Ganon

I think you put me on track with regards to using "r" to access each member
of the vector. I eventually came up with the following which runs and does what I need it to, although I'm sceptical that its the most effcient way to compile this code :

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <ios>
#include <string>
#include <vector>

using std::cin; using std::sort;
using std::cout; using std::endl;
using std::string; using std::streamsize ;
using std::vector; using std::setprecisi on;

int main()
{
// ask for and read the user's name
cout << "Please enter your first name: ";
string name;
cin >> name;
cout << "Hello, " << name << "!" << endl;

// ask for and read family member's names
cout << "Please enter all your family members names, "
"followed by end-of-file: ";
vector<string> family;
string x;
// invariant:famil y contains all family names read so far
while (cin >> x)
family.push_bac k(x);

// check that the user entered some names
typedef vector<string>: :size_type vec_sz;
vec_sz size = family.size();
if (size == 0) {
cout << endl << "You must enter two or more family names. "
"Please try again." << endl;
system("PAUSE") ;
return 1;
}
// sort the names
sort(family.beg in(), family.end());
cout << endl;

// declare variable of type iterator to read through all elements
// declare min and max variables setting min to 100 and max to 0
int max = 0;
int min = 100;
for (vector<string> ::iterator i = family.begin(); i != family.end(); ++i)
{
if ((*i).length() > max) { // work out the longest name by testing
max = (*i).length(); //the length of each input against the last
}
if ((*i).length() < min) { //work out the shortest name by testing the
min = (*i).length(); //the length of each input against the last
}
}
cout << "Shortest: " << min << endl;
cout << "Longest: " << max << endl;


system("PAUSE") ;
return 0;
}

Thanks again, been stuck on this one for a while.

Cheers

M

[Ganon11]

Well, I'm not sure if you needed to use iterators, but that certainly works, and isn't that all that matters?

Glad to have helped!