C/C++ reading and writing long strings to files - c++

Question

I have a list of cities that I'm formatting like this:
{town, ...},
{...},
...
Reading and building each town and creating town1, town2,.... works
The problem is when I output it, 1st line works {town, ...}, but the second line crashes.
Any idea why?
I have [region] [town] (excel table).
So each region repeats by how many towns are in it.
Each file has 1 region/town per line.
judete contains each region repeated 1 time.
AB
SD
PC
....
orase contains the towns list.
town1
town2
....
orase-index contains the region of each town
AB
AB
AB
AB
SD
SD
SD
PC
PC
...
I want an output like this {"town1", "town2", ...} and each row (row 5) contains the town that belong to the region from judete at the same row (row 5).
Here's my code:
#include<stdio.h>
#include<string.h>
char judet[100][100];
char orase[50][900000];
char oras[100], ceva[100];
void main ()
{
int i=0, nr;
FILE *judete, *index, *ORASE, *output;
judete = fopen("judete.txt", "rt");
index = fopen("orase-index.txt", "rt");
ORASE = fopen("orase.txt", "rt");
output = fopen("output.txt", "wt");
while( !feof(judete) )
{
fgets(judet[i], 100, judete);
i++;
}
nr = i;
char tmp[100];
int where=0;
for(i=0;i<nr;i++)
strcpy(orase[i],"");
while( !feof(index) )
{
fgets(tmp, 100, index);
for(i=0;i<nr;i++)
{
if( strstr(judet[i], tmp) )
{
fgets(oras, 100, ORASE);
strcat(ceva, "\"");
oras[strlen(oras)-1]='\0';
strcat(ceva, oras);
strcat(ceva, "\", ");
strcat(orase[i], ceva);
break;
}
}
}
char out[900000];
for(i=0;i<nr;i++)
{
strcpy(out, "");
strcat(out, "{");
strcat(out, orase[i]); //fails here
fprintf(output, "%s},\n", out);
}
}
The result I get from running the code is:
Unhandled exception at 0x00D4F7A9 (msvcr110d.dll) in orase-judete.exe: 0xC0000005: Access violation writing location 0x00A90000.

Answer 1

You don't clear orase array, beacause your loop
for(i-0;i<nr;i++)
strcpy(orase[i],"");
by mistake ('-' instead of '=') executes 0 times.

Answer 2

I think you need to start by making up your mind whether you're writing C or C++. You've tagged this with both, but the code looks like it's pure C. While a C++ compiler will accept most C, the result isn't what most would think of as ideal C++.
Since you have tagged it as C++, I'm going to assume you actually want (or all right with) C++ code. Well written C++ code is going to be enough different from your current C code that it's probably easier to start over than try to rewrite the code line by line or anything like that.
The immediate problem I see with doing that, however, is that you haven't really specified what you want as your output. For the moment I'm going to assume you want each line of output to be something like this: "{" <town> "," <town> "}".
If that's the case, I'd start by noting that the output doesn't seem to depend on your judete file at all. The orase and orase-index seem to be entirely adequate. For that, our code can look something like this:
#include <iostream>
#include <string>
#include <iterator>
#include <fstream>
#include <vector>
// a class that overloads `operator>>` to read a line at a time:
class line {
std::string data;
public:
friend std::istream &operator>>(std::istream &is, line &l) {
return std::getline(is, l.data);
}
operator std::string() const { return data; }
};
int main() {
// open the input files:
std::ifstream town_input("orase.txt");
std::ifstream region_input("orase-index.txt");
// create istream_iterator's to read from the input files. Note
// that these iterate over `line`s, (i.e., objects of the type
// above, so they use its `operator>>` to read each data item).
//
std::istream_iterator<line> regions(region_input),
towns(town_input),
end;
// read in the lists of towns and regions:
std::vector<std::string> town_list {towns, end};
std::vector<std::string> region_list {regions, end};
// write out the file of town-name, region-name:
std::ofstream result("output.txt");
for (int i=0; i<town_list.size(); i++)
result << "{" << town_list[i] << "," << region_list[i] << "}\n";
}
Noe that since this is C++, you'll typically need to save the source as something.cpp instead of something.c for the compiler to recognize it correctly.
Edit: Based on the new requirements you've given in the comments, you apparently want something closer to this:
#include <iostream>
#include <string>
#include <iterator>
#include <fstream>
#include <vector>
#include <map>
// a class that overloads `operator>>` to read a line at a time:
class line {
std::string data;
public:
friend std::istream &operator>>(std::istream &is, line &l) {
return std::getline(is, l.data);
}
operator std::string() const { return data; }
};
int main() {
// open the input files:
std::ifstream town_input("orase.txt");
std::ifstream region_input("orase-index.txt");
// create istream_iterator's to read from the input files. Note
// that these iterate over `line`s, (i.e., objects of the type
// above, so they use its `operator>>` to read each data item).
//
std::istream_iterator<line> regions(region_input),
towns(town_input),
end;
// read in the lists of towns and regions:
std::vector<std::string> town_list (towns, end);
std::vector<std::string> region_list (regions, end);
// consolidate towns per region:
std::map<std::string, std::vector<std::string> > consolidated;
for (int i = 0; i < town_list.size(); i++)
consolidated[region_list[i]].push_back(town_list[i]);
// write out towns by region
std::ofstream output("output.txt");
for (auto pos = consolidated.begin(); pos != consolidated.end(); ++pos) {
std::cout << pos->first << ": ";
std::copy(pos->second.begin(), pos->second.end(),
std::ostream_iterator<std::string>(output, "\t"));
std::cout << "\n";
}
}

Answer 3

Notice that ceva is never initialized.
Instead of using strcpy to initialize strings, I would recommend using static initialization:
char ceva[100]="";