Vector subscription out of range C++

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I am working on a program that reads integers from file, stores it in vector and use count sort to sort the integers and write them in new file. My problem ocurs when i run Countsort function, the breakpoint happens at this for loop, all the numbers are counted correctly as i can see in the breakepoint

this is the loop that breakpoint occurs:

for (int i = 0; i < C.size(); i++) {
    C[A[i]] = C[A[i]] + 1;
}

my code looks like this:

C++

//COUNT SORT
void countsort() {

    int max = A[0];

    for (int i = 1; i < A.size(); i++) {
        if (A[i] > max) { 
            max = A[i];
        }
    }

    vector<int> C(max + 1);
    vector<int> B(A.size()); 

    for (int i = 0; i < C.size(); i++) {
        C[A[i]] = C[A[i]] + 1;
    }

    for (int i = 1; i < C.size(); i++) {
        C[i] = C[i] + C[i + 1];
    }

    for (int i = C.size() - 1; i >= 0; i--) {
        B[C[A[i]] - 1] = A[i];
        C[A[i]] = C[A[i]] - 1;
    }

    for (int i = 0; i < A.size(); i++) {
        A[i] = B[i];
    }
}

[Update]
ok im gonna post you full code here, comments are not in english thats why i deleted them:

C++

#include "stdafx.h"
#include <iostream>
#include <cstdlib>
#include <fstream>
#include <vector>

using namespace std;

vector<int> A;
vector<int> C;
vector<int> B;

//MENU
void menu() {
	cout << endl;
	cout << "<opcija> - 0 = Beri iz vhoda" << endl;
	cout << "<opcija> - 1 = Counting sort" << endl;
	cout << "<opcija> - 2 = Roman sort" << endl;
	cout << "<opcija> - 3 = Izhod podatkov v txt" << endl;
	cout << "<opcija> - 4 = IZHOD" << endl;
	cout << endl;
}

//BRANJE VHODA
void beri() {

	ifstream file;
	file.open("primer_vhoda.txt"); //branje datoteke vhod.txt
	int st; //stevec stevil

	if (!file.is_open()) { //ce datoteke ne odpre
		cout << "Datoteke ni mogoce najti!" << endl; //izpise napako
	}

	while (file >> st) { //medtem ko bere stevila
		A.push_back(st); //jih shranjuje v vektor
	}
}

//COUNT SORT
void countsort() {

	int max = A[0]; //vrednosti inicializiramo na 0

	//poiscemo najvecje stevilo v A
	for (int i = 1; i < A.size(); i++) { //sprehodimo se po A
		if (A[i] > max) { 
			max = A[i];
		}
	}
	//cout << "NAJVECJE STEVILO JE: " << max << endl; SAMO ZA TEST
	vector<int> C(max + 1); //pomozno polje velikosti max + 1 --> max je najvecje stevilo v A
	vector<int> B(A.size()); //koncno polje B enake velikosti kot polje A

	for (int i = 0; i < C.size(); i++) {
		C[A[i]] = C[A[i]] + 1;
	}

	for (int i = 1; i < C.size(); i++) {
		C[i] = C[i] + C[i + 1];
	}

	for (int i = C.size() - 1; i >= 0; i--) {
		B[C[A[i]] - 1] = A[i];
		C[A[i]] = C[A[i]] - 1;
	}

	for (int i = 0; i < A.size(); i++) {
		A[i] = B[i];
	}


	/*for (int i = 0; i < C.size(); i++) { //vrednosti v C inicializiramo na 0
		C[i] = 0;
	}

	for (int i = 0; i < A.size(); i++) {
		C[A[i]] = C[A[i]] + 1;
	}

	for (int i = C.size() - 1; i > 0; i-- ) {
		C[i] = C[i] + C[i - 1];
	}

	for (int i = A.size() - 1; i >= 0; i--) {
		B[C[A[i]] - 1] = A[i];
		C[A[i]] = C[A[i]] - 1;
		cout << B[i] << " ";
	}*/
}

//IZPIS STEVIL V TXT
void izpisi() {
	int st; //stevec stevil
	ofstream file("izhod.txt"); //naredimo novo datoteko
	if (file.is_open()) { //ko je datoteka odprta
		for (int i = 0; i < B.size(); i++) { //preletimo vektor
			file << B[i] << " "; //zapisemo stevila v datoteko
		}
	}
}

//MAIN
int main()
{
	int izbira = 0;
	vector <int> A;
	vector <int> B;


	do {
		menu();
		cout << endl << "Izbira: ";
		cin >> izbira;
		switch (izbira) {
		case 0:
			beri();
			break;
		case 1:
			countsort();
			break;
		case 2:
			//izpisivector();
		case 3:
			izpisi();
			break;
		case 4:
			break;
		default:
			cout << "Napacna izbira!";
			break;
		}
	} while (izbira != 4);
	{
		system("PAUSE");
		return EXIT_SUCCESS;
	}
}

</vector></fstream></cstdlib></iostream>

What I have tried:

I searched, but couldnt find my answer.

Posted 12-Mar-16 10:53am

vidusi

Updated 12-Mar-16 13:18pm

Patrice T

v2

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Patrice T · Answer 1 · 2016-03-12T11:07:00

Solution 1

C++

for (int i = 0; i < C.size(); i++) {
    C[A[i]] = C[A[i]] + 1;
}

How do you know that A.size() is at least as big as C.size() ?
Because the code fails when if A.size() < C.size().

[update]
correction for this part

C++

for (int i = 0; i < A.size(); i++) {
    C[A[i]] = C[A[i]] + 1;
}

Posted 12-Mar-16 11:07am

Patrice T

Updated 12-Mar-16 13:57pm

v2

Comments

vidusi 12-Mar-16 17:15pm

hmm, i guess i dont know that, how can i get rid of that error in this case?

Patrice T 12-Mar-16 17:20pm

A is define in code you didn't provide!
Can you explain what this code is doing ?

vidusi 12-Mar-16 18:22pm

A is a global vector, my program is reading integers from a file and stores them in vector A, then i do countsort of those numbers.

Patrice T 12-Mar-16 18:51pm

Need to see a complete piece of code to understand what you do.
Comments in code may help too

vidusi 12-Mar-16 19:02pm

ok im gonna post you full code here, comments are not in english thats why i deleted them:

#include "stdafx.h"
#include <iostream>
#include <cstdlib>
#include <fstream>
#include <vector>

using namespace std;

vector<int> A;
vector<int> C;
vector<int> B;

//MENU
void menu() {
cout << endl;
cout << "<opcija> - 0 = Beri iz vhoda" << endl;
cout << "<opcija> - 1 = Counting sort" << endl;
cout << "<opcija> - 2 = Roman sort" << endl;
cout << "<opcija> - 3 = Izhod podatkov v txt" << endl;
cout << "<opcija> - 4 = IZHOD" << endl;
cout << endl;
}

//BRANJE VHODA
void beri() {

ifstream file;
file.open("primer_vhoda.txt"); //branje datoteke vhod.txt
int st; //stevec stevil

if (!file.is_open()) { //ce datoteke ne odpre
cout << "Datoteke ni mogoce najti!" << endl; //izpise napako
}

while (file >> st) { //medtem ko bere stevila
A.push_back(st); //jih shranjuje v vektor
}
}

//COUNT SORT
void countsort() {

int max = A[0]; //vrednosti inicializiramo na 0

//poiscemo najvecje stevilo v A
for (int i = 1; i < A.size(); i++) { //sprehodimo se po A
if (A[i] > max) {
max = A[i];
}
}
//cout << "NAJVECJE STEVILO JE: " << max << endl; SAMO ZA TEST
vector<int> C(max + 1); //pomozno polje velikosti max + 1 --> max je najvecje stevilo v A
vector<int> B(A.size()); //koncno polje B enake velikosti kot polje A

for (int i = 0; i < C.size(); i++) {
C[A[i]] = C[A[i]] + 1;
}

for (int i = 1; i < C.size(); i++) {
C[i] = C[i] + C[i + 1];
}

for (int i = C.size() - 1; i >= 0; i--) {
B[C[A[i]] - 1] = A[i];
C[A[i]] = C[A[i]] - 1;
}

for (int i = 0; i < A.size(); i++) {
A[i] = B[i];
}

/*for (int i = 0; i < C.size(); i++) { //vrednosti v C inicializiramo na 0
C[i] = 0;
}

for (int i = 0; i < A.size(); i++) {
C[A[i]] = C[A[i]] + 1;
}

for (int i = C.size() - 1; i > 0; i-- ) {
C[i] = C[i] + C[i - 1];
}

for (int i = A.size() - 1; i >= 0; i--) {
B[C[A[i]] - 1] = A[i];
C[A[i]] = C[A[i]] - 1;
cout << B[i] << " ";
}*/
}

//IZPIS STEVIL V TXT
void izpisi() {
int st; //stevec stevil
ofstream file("izhod.txt"); //naredimo novo datoteko
if (file.is_open()) { //ko je datoteka odprta
for (int i = 0; i < B.size(); i++) { //preletimo vektor
file << B[i] << " "; //zapisemo stevila v datoteko
}
}
}

//MAIN
int main()
{
int izbira = 0;
vector <int> A;
vector <int> B;

do {
menu();
cout << endl << "Izbira: ";
cin >> izbira;
switch (izbira) {
case 0:
beri();
break;
case 1:
countsort();
break;
case 2:
//izpisivector();
case 3:
izpisi();
break;
case 4:
break;
default:
cout << "Napacna izbira!";
break;
}
} while (izbira != 4);
{
system("PAUSE");
return EXIT_SUCCESS;
}
}

Serkan Onat · Answer 2 · 2016-03-12T13:07:00

Solution 2

The problem is your vector definiton

C++

vector<int> C(max + 1);

consider you have 3 items in vector A
10,20,100

Here you define a max value

C++

int max = A[0];
 
for (int i = 1; i < A.size(); i++) {
    if (A[i] > max) 
    { 
        max = A[i];
    }
}

now size of vector is 3 , and the variable max contains 100
and your vector with 101 items (preallocated)

vector<int> C(max + 1);

and your code as following

C++

vector<int> C(max + 1);
vector<int> B(A.size()); 
 
for (int i = 0; i < C.size(); i++) 
{
    C[A[i]] = C[A[i]] + 1;
}

size of C is 101 whereas size of A 3 , which causing access violation

you vector definition should be like below

vector<int> C(A.size());
vector<int> B(A.size()); </int>

Posted 12-Mar-16 13:07pm

Serkan Onat

Comments

vidusi 12-Mar-16 19:26pm

even tho i change the vectors like you mentioned i am getting the same error... at the same for loop. The thing is i need that max + 1 values for C array as i am doing counting sort.

Serkan Onat 12-Mar-16 19:49pm

i have pointed out the general issue in your code , so you have scope errors
i am not going to fix your homework sorry

but consider following ,according to my example 10,20,100

i = 2; which points to value of 100 and size of C is 3 (even after you made the change i mentioned)

C[A[i]] = C[A[i]] + 1;

translates to

C[100] = C[100] + 1;

but there is no room at index 100 , currently C contains only 3 items and max index is 2 (zero based)

you can use temporary vectors to, fix your problems

vidusi 12-Mar-16 19:56pm

i never considered that you guys will be fixing my errors, i just wanted an explanation why this error is happening as i havent found something similar.. I apreciate your help though.