C++ Vector Crashing [closed] - c++

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Evening All,
My following code:
#include <iostream>
#include <vector>
#include <fstream>
using namespace std;
const char NEWLINE = 0x0D + 0x0A;
int main() {
int headerCount;
char response;
int x = 0;
int i = 0;
string header[headerCount];
cout << "How many columns appear in you file: ";
cin >> headerCount;
cout << "There are " << headerCount << " columns in your file? (Y/N): ";
cin >> response;
if(response == 'Y'){
cout << endl << "Okay" << endl;
ofstream myfile;
myfile.open("example.csv", ios::binary | ios::out);
string vals;
vector< vector<string> > buff;
// To set values
while(i != 3){
vector<string> temp;
while(x != headerCount){
if (i == 0){
cout << "What is header number " << (x + 1) << endl;
} else {
cout << "What is person " << i << "'s " << header[x] << ":";
}
cin >> vals;
if (i == 0) header[x] = vals;
temp.push_back("\"" + vals + "\"");
if (x != (headerCount - 1)) { temp.push_back(","); }
x++;
}
buff.push_back(temp); // Store the array in the buffer
x = 0;
i++;
}
//To access values
for(vector<vector<string> >::iterator it = buff.begin(); it != buff.end(); ++it){
//it is now a pointer to a vector<int>
for(vector<string>::iterator jt = it->begin(); jt != it->end(); ++jt){
// jt is now a pointer to an integer.
myfile << *jt;
}
myfile << "\r\n";
}
myfile.close();
} else {
cout << endl << "oh";
}
return 0;
}
Crashes on its fourth iteration.
E.g. value[0][4]
Any ideas? I am reasonably new to vectors. This code causes Code::Blocks to display my application as "not responding". Really Lost at the moment!
I know there are probably plenty of similar posts but I have been trawling the web for hours.

Answer 1

First, you must thank #40two who quickly spotted the main issues.
So add the missing include. Then, define your variable header as a vector to allow for dynamic sizing. However, do this AFTER your cin reading, in order to make sure the variable is initialised and not random:
cin >> headerCount; // existing line
vector<string> header(headerCount); // definition in a new place
Then it should run without crashing (tested with VC2013)

Answer 2

As #40two mentioned, the real issue is that you cannot variable sized arrays in C++. There is huge scope to improve the code significantly. To get you going quickly, see the fixed up code below.
#include <iostream>
#include <vector>
#include <fstream>
using namespace std;
const char NEWLINE = 0x0D + 0x0A;
int main() {
int headerCount;
char response;
int x = 0;
int i = 0;
cout << "How many columns appear in you file: ";
cin >> headerCount;
cout << "There are " << headerCount << " columns in your file? (Y/N): ";
cin >> response;
if(response == 'Y'){
cout << endl << "Okay" << endl;
ofstream myfile;
myfile.open("example.csv", ios::binary | ios::out);
string vals;
vector< vector<string> > buff;
// To set values
while(i != 3){
vector<string> temp;
while(x != headerCount)
{
string header;
if (i == 0){
cout << "What is header number " << (x + 1) << endl;
} else {
cout << "What is person " << i << "'s " << header << ":";
}
cin >> vals;
if (i == 0)
header = vals;
temp.push_back("\"" + vals + "\"");
if (x != (headerCount - 1)) { temp.push_back(","); }
x++;
}
buff.push_back(temp); // Store the array in the buffer
x = 0;
i++;
}
//To access values
for(vector<vector<string> >::iterator it = buff.begin(); it != buff.end(); ++it){
//it is now a pointer to a vector<int>
for(vector<string>::iterator jt = it->begin(); jt != it->end(); ++jt){
// jt is now a pointer to an integer.
myfile << *jt;
}
myfile << "\r\n";
}
myfile.close();
} else {
cout << endl << "oh";
}
return 0;
}