C++ Unable to assign Character Array Variable to String Variable - c++

Question

I am in need of assistance.
I am trying to create a vector structure where the string contents inside of a char array get automatically assign to another STRING variable within the same structure.
After countless hours, I have not been able to figure it out. When I used function such as string(). It doesn't copy anything. I can't seem to assign char variable to string variable. Please advise.
#include <iostream>
#include <ctime>
#include <fstream>
#include <string>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;
const int NAME_SIZE = 25;
struct tableInfo
{
char name2[NAME_SIZE];
string name = str(name2); // I need name string to equal name2 character variable
string info;
string link;
};
vector<tableInfo> table(6);
bool compareByWord(const tableInfo &lhs, const tableInfo &rhs);
int main()
{
cin.getline(table[0].name2, 51);
cin.getline(table[1].name2, 51);
cin.getline(table[2].name2, 51);
cin.getline(table[3].name2, 51);
cin.getline(table[4].name2, 51);
sort(table.begin(), table.end(), compareByWord);
cout << table[0].name << endl;
cout << table[1].name << endl;
cout << table[2].name << endl;
cout << table[3].name << endl;
cout << table[4].name << endl;
}
bool compareByWord(const tableInfo &lhs, const tableInfo &rhs)
{
unsigned int length = lhs.name.length();
if (rhs.name.length() < length)
length = rhs.name.length();
int sameLetters = 0;
for (unsigned int i = 0; i < length; ++i)
{
if (sameLetters == length)
return false;
if (tolower(lhs.name[i]) == tolower(rhs.name[i]))
{
++sameLetters;
continue;
}
return(lhs.name[i] < rhs.name[i]);
return(lhs.name[i] < rhs.name[i]);
}
return false;
}

Answer 1

If you want something to happen in a structure (or class), consider making sure it happens by using the constructor. You will need to change your vector so you can no longer default construct the struture, but that's ok.
This works, by enforcing the two fields contain identical data (not withstanding 25 no being long enough):
const int NAME_SIZE = 25;
struct tableInfo
{
tableInfo(char * whatever); //Make it so
char name2[NAME_SIZE];
string name;
string info;
string link;
};
tableInfo::tableInfo(char *whatever)
: name(whatever)
{
strncpy(name2, whatever, NAME_SIZE); //Now they match - unless whatever was too big
}
//vector<tableInfo> table(6);//no longer ok with the non-default constructor
bool compareByWord(const tableInfo &lhs, const tableInfo &rhs);
int main()
{
vector<tableInfo> table;
for (int i = 0; i < 5; ++i)
{
char name2[NAME_SIZE];
cin.getline(name2, 51); //Do you really mean 51?
// It's smaller than NAME_SIZE
table.emplace_back(name2);
}
sort(table.begin(), table.end(), compareByWord);
cout << table[0].name << endl;
cout << table[1].name << endl;
cout << table[2].name << endl;
cout << table[3].name << endl;
cout << table[4].name << endl;
}

Answer 2

How about doing like this:
struct tableInfo
{
char name2[NAME_SIZE];
string name;
string info;
string link;
tableInfo(const char* in_name)
{
memset(name2, 0, NAME_SIZE);
strncpy(name2, in_name, NAME_SIZE - 1);
name = string(name2);
}
};
How to use:
char tmp[NAME_SIZE];
cin.getline(tmp, 51);
table[0] = tableInfo(tmp);

Answer 3

I argue that you don't even need an array in the struct. Just use std::string. getline supports reading into a std::string and you can access individual characters using str[]. If you need to get a pointer to the data you can use str.c_str().
If you really need to use an array in the struct you can create a member function to return a std::string:
struct tableName {
char name[NAME_SIZE];
std::string info;
std::string link;
std::string nameString() const { return name; }
};