Program crashed after end of scope - c++

Question

I was confused from this following codes, it's creating crash that I fully don't understand.
#include <stdio.h>
#include <string.h>
#include <vector>
using namespace std;
struct Store
{
int pos;
char character;
};
vector<struct Store> v_store;
void swap_inside_vector(vector<struct Store> &v_store, int a, int b)
{
struct Store tmp = v_store[b];
v_store[b] = v_store[a];
v_store[a] = tmp;
}
int find_inside_vector(vector<struct Store> &v_store, int pos)
{
for(int i = 0; i < v_store.size(); i++)
{
if(v_store[i].pos == pos)
return i;
}
return -1;
}
void swap_most_right_to_most_left(vector<struct Store> &v_store)
{
struct Store tmp = v_store[v_store.size() - 1];
for(int i = v_store.size(); i > 0; i--)
{
v_store[i] = v_store[i-1];
}
v_store[0] = tmp;
}
void print_char_inside_vector(vector<struct Store> &v) // used for debugging
{
for(int i = 0; i < v.size(); i++)
{
printf("%C", v[i].character);
}
}
int check_vector_original_state(vector<struct Store> &v_store)
{
for(int i = 1; i <= v_store.size(); i++)
{
if(v_store[i-1].pos != i)
return 0;
}
return 1;
}
int main()
{
int n;
char input_str[100];
for(int q = 1; scanf("\n%d", &n), n; q++)
{
scanf("%s", input_str);
vector<struct Store> original_store, tmp_origin_store, v_store;
vector<vector<struct Store> > store_vector;
original_store.clear();
tmp_origin_store.clear();
v_store.clear();
store_vector.clear();
for(int i = 1; i <= strlen(input_str); i++)
{
struct Store s = {.pos = i, .character = input_str[i-1]};
original_store.push_back(s);
}
tmp_origin_store = original_store;
v_store = tmp_origin_store;
for(int i = 1, current_pos = 0; i <= n; i++, current_pos++)
{
int vector_index = find_inside_vector(v_store, tmp_origin_store[current_pos].pos);
//printf("Processing -> [%d], Current Pos -> [%d]\n", i, current_pos);
for(int z = 0; z < (current_pos + 1); z++)
{
if(vector_index == (v_store.size() - 1))
{
swap_most_right_to_most_left(v_store);
vector_index = 0;
}
else
{
swap_inside_vector(v_store, vector_index, vector_index + 1);
vector_index++;
}
//print_char_inside_vector(v_store);
//puts("");
}
//puts("");
store_vector.push_back(v_store);
if(check_vector_original_state(v_store))
{
store_vector.push_back(v_store);
break;
}
if(current_pos == (v_store.size() - 1))
{
tmp_origin_store = v_store;
current_pos = -1;
}
}
// debugging
/*for(int x = 0; x < store_vector.size(); x++)
{
printf("[%d] -> ", x + 1);
print_char_inside_vector(store_vector[x]);
puts("");
}*/
int target_pos;
if(store_vector.size() < n)
{
target_pos = n % store_vector.size();
}
else
{
target_pos = store_vector.size();
}
if(target_pos == 0)
{
printf("%d. ", q);
print_char_inside_vector(store_vector[0]);
puts("");
}
else
{
printf("%d. ", q);
print_char_inside_vector(store_vector[target_pos - 1]);
puts("");
}
}
}
What this program does is accepting input from STDIN, process it, and output it on STDOUT.
My expecting input is
3 ABCD
13 ACM
3 DAEQD
4 FAEQS
Expected output is
1. CABD
2. CAM
3. DAQDE
4. FQASE
My problem is, after inputing fourth input into STDIN, and after output is being shown, crash occured.
C:\Study>h.exe
3 ABCD
1. CABD
13 ACM
2. CAM
3 DAEQD
3. DAQDE
4 FAEQS
4. FQASE
0 [main] h 9092 cygwin_exception::open_stackdumpfile: Dumping stack trace to h.exe.stackdump
From my observation, I think the problem is at the vector, but it's just a guess.

Answer 1

Your code didn't compile :
//struct Store s = { .pos = i, .character = input_str[i - 1] }; // syntax not recongnized
Store s = { i, input_str[i - 1] }; // replaced with this.
After fixing this, the debugging immediatly identified an out of bound problem on a vector, which could lead to memory corruption issue. It's in swap_most_right_to_most_left():
for (int i = v_store.size(); i > 0; i--) { // you start with i=v_store.size()
v_store[i] = v_store[i - 1]; // and you immediately get out of bounds !
}
If you correct this instruction to :
for (int i = v_store.size()-1; i > 0; i--) {
v_store[i] = v_store[i - 1];
}
you'll get the expected output for the given input.