how can i solve valgrind memory leak error
Question
I have 3 files in total and I get the output I want but I am getting a memory leak error when run with Valgrind.
main.cpp
#include<iostream>
#include<iomanip>
#include "Car.h"
using namespace std;
using namespace sdds;
int main()
{
const int num_cars = 6;
Car carInventory[num_cars] = {
{},
{"suv", "volvo", "xc90"},
{"Truck", "Ford", "F 150", 2021, 105, 55000},
{"Sedan", "BMW", "M550i", 2022, 101, 91000},
{"Truck", "Tesla", "Cybertruck", 2021, 102, 65000},
{"Sedan", "BMW", "M550i"}
};
if (carInventory[2].setInfo("SUV", "Volvo", "XC90", 2019, 109, 80000).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
if (carInventory[1].setInfo(nullptr, "Volvo", "XC90", 2019, 109, 80000).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
if (carInventory[1].setInfo("SUV", nullptr, "XC90", 2019, 109, 80000).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
if (carInventory[1].setInfo("SUV", "Volvo", nullptr, 2019, 109, 80000).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
if (carInventory[1].setInfo("SUV", "Volvo", "XC90", 1934, 109, 80000).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
if (carInventory[1].setInfo("SUV", "Volvo", "XC90", 2019, 1, 80000).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
if (carInventory[1].setInfo("SUV", "Volvo", "XC90", 2019, 109, 0).isValid()) {
cout << "Information was set correctly!" << endl;
}
else {
cout << "Information was set incorrectly!" << endl;
}
cout << setw(60) << "----- Testing printInfo function -----" << endl << endl;
cout << "| Type | Brand | Model | Year | Code | Price |" << endl;
cout << "+------------+------------------+------------------+------+------+-----------+" << endl;
carInventory[4].printInfo();
cout << endl << endl;
cout << setw(60) << "----- Car Inventory Information -----" << endl << endl;
cout << "| Type | Brand | Model | Year | Code | Price |" << endl;
cout << "+------------+------------------+------------------+------+------+-----------+" << endl;
print(carInventory, num_cars);
if (has_invalid(carInventory, num_cars)) {
cout << endl;
cout << setfill('*') << setw(60) << "*" << endl;
cout << "* WARNING: There are invalid data in the inventory! *" << endl;
cout << setfill('*') << setw(60) << "*" << endl;
}
if (has_similar(carInventory, num_cars)) {
cout << endl;
cout << setfill('+') << setw(60) << "+" << endl;
cout << "+ WARNING: There are similar entries in the inventory! +" << endl;
cout << setfill('+') << setw(60) << "+" << endl;
}
return 0;
}
Car.h
#ifndef SDDS_CAR_H
#define SDDS_CAR_H
namespace sdds{
class Car{
private:
char *m_type;
char *m_brand;
char *m_model;
int m_year;
int m_code;
double m_price;
public:
Car();
Car(const char *type, const char *brand, const char *model, int year = 2022, int code = 100, double price = 1);
~Car();
void resetInfo();
Car& setInfo(const char *type, const char *brand, const char *model,int yera,int code, double price);
void printInfo() const;
bool isValid() const;
bool isSimilarTo(const Car& car) const;
};
bool has_similar(const Car car[], const int num_cars);
bool has_invalid(const Car car[], const int num_cars);
void print(const Car car[], const int num_cars);
}
#endif
Car.cpp
#include <bits/stdc++.h>
#include "Car.h"
using namespace std;
namespace sdds{
void Car::resetInfo(){
m_type = nullptr;
m_brand = nullptr;
m_model = nullptr;
m_year = 0;
m_code = 0;
m_price = 0;
}
Car::Car(){
resetInfo();
}
Car::Car(const char* type, const char* brand, const char* model, int year, int code, double price){
if(type != nullptr && brand != nullptr && model != nullptr && year > 0 && code > 0 && price > 0){
m_type = new char[strlen(type) + 1];
strcpy(m_type, type);
m_brand = new char[strlen(brand) + 1];
strcpy(m_brand, brand);
m_model = new char[strlen(model) + 1];
strcpy(m_model, model);
m_year = year;
m_code = code;
m_price = price;
}
else{
cout<<"any time here\n";
resetInfo();
}
}
Car::~Car(){
delete[] m_type;
delete[] m_brand;
delete[] m_model;
m_type = nullptr;
m_brand = nullptr;
m_model = nullptr;
}
Car& Car::setInfo(const char *type,const char *brand, const char *model,int year,int code,double price){
this->resetInfo();
if(type == nullptr || brand == nullptr || model == nullptr || year < 1990 || code <= 99 || price <= 0){
// this->resetInfo();
return *this;
}
else{
m_type = new char[strlen(type) + 1];
strcpy(m_type, type);
m_brand = new char[strlen(brand) + 1];
strcpy(m_brand, brand);
m_model = new char[strlen(model) + 1];
strcpy(m_model, model);
m_year = year;
m_code = code;
m_price = price;
}
return *this;
}
void Car::printInfo()const{
//cout << "| " << m_type << setw(8) << "| " << m_brand << setw(14) << "| " << m_model << setw(9) << " | " << m_year << setw(3) << "| " << m_code << setw(4) << " | " << m_price << setw(6) << " |" << endl;
if(m_type != nullptr && m_brand != nullptr && m_model != nullptr && m_year >= 1990 && m_code > 99 && m_price > 0){
printf("| %-10s | %-15s | %-15s | %-4d | %4d | %8.2lf |\n",m_type,m_brand,m_model,m_year,m_code,m_price);
}
}
bool Car::isValid()const{
//return m_type != nullptr && m_brand != nullptr && m_model != nullptr && m_year > 0 && m_code > 0 && m_price > 0;
if(m_type != nullptr && m_brand != nullptr && m_model != nullptr && m_year >= 1990 && m_code >= 100 && m_price > 0){
//cout<<m_type<<" "<<m_brand<<" "<<m_model<<" "<<m_year<<" "<<m_code<<" "<<m_price<<endl;
return true;
}
else{
//cout<<m_type<<" "<<m_brand<<" "<<m_model<<" "<<m_year<<" "<<m_code<<" "<<m_price<<endl;
return false;
}
}
bool Car::isSimilarTo(const Car& other)const{
if(m_type == other.m_type && m_brand == other.m_brand && m_model == other.m_model && m_year == other.m_year){
return true;
}
else{
return false;
}
return false;
}
bool has_similar(const Car car[],const int num_cars){
for(int i = 0; i < num_cars; i++){
for(int j = i + 1; j < num_cars; j++){
if(car[i].isSimilarTo(car[j])){
return true;
}
}
}
return false;
}
bool has_invalid(const Car car[], const int num_cars){
for(int i = 0; i < num_cars; i++){
if(!car[i].isValid()){
return true;
}
}
return false;
}
void print(const Car car[], const int num_cars){
for(int i = 0; i < num_cars; i++){
car[i].printInfo();
}
}
}
Here is the output I want And I got it
Information was set correctly!
Information was set incorrectly!
Information was set incorrectly!
Information was set incorrectly!
Information was set incorrectly!
Information was set incorrectly!
Information was set incorrectly!
----- Testing printInfo function -----
| Type | Brand | Model | Year | Code | Price |
+------------+------------------+------------------+------+------+-----------+
| Truck | Tesla | Cybertruck | 2021 | 102 | 65000.00 |
----- Car Inventory Information -----
| Type | Brand | Model | Year | Code | Price |
+------------+------------------+------------------+------+------+-----------+
| SUV | Volvo | XC90 | 2019 | 109 | 80000.00 |
| Sedan | BMW | M550i | 2022 | 101 | 91000.00 |
| Truck | Tesla | Cybertruck | 2021 | 102 | 65000.00 |
| Sedan | BMW | M550i | 2022 | 100 | 1.00 |
************************************************************
* WARNING: There are invalid data in the inventory! *
************************************************************
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ WARNING: There are similar entries in the inventory! +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
But here is the memory leak error
==86467==
==86467== HEAP SUMMARY:
==86467== in use at exit: 32 bytes in 6 blocks
==86467== total heap usage: 19 allocs, 13 frees, 72,806 bytes allocated
==86467==
==86467== 4 bytes in 1 blocks are definitely lost in loss record 1 of 6
==86467== at 0x4C2AC38: operator new[](unsigned long) (vg_replace_malloc.c:433)
==86467== by 0x400C2C: sdds::Car::Car(char const*, char const*, char const*, int, int, double) (Car.cpp:27)
==86467== by 0x401229: main (main_prof.cpp:23)
==86467==
==86467== 5 bytes in 1 blocks are definitely lost in loss record 2 of 6
==86467== at 0x4C2AC38: operator new[](unsigned long) (vg_replace_malloc.c:433)
==86467== by 0x400C98: sdds::Car::Car(char const*, char const*, char const*, int, int, double) (Car.cpp:31)
==86467== by 0x401229: main (main_prof.cpp:23)
==86467==
==86467== 5 bytes in 1 blocks are definitely lost in loss record 3 of 6
==86467== at 0x4C2AC38: operator new[](unsigned long) (vg_replace_malloc.c:433)
==86467== by 0x400C61: sdds::Car::Car(char const*, char const*, char const*, int, int, double) (Car.cpp:29)
==86467== by 0x40126D: main (main_prof.cpp:23)
==86467==
==86467== 6 bytes in 1 blocks are definitely lost in loss record 4 of 6
==86467== at 0x4C2AC38: operator new[](unsigned long) (vg_replace_malloc.c:433)
==86467== by 0x400C61: sdds::Car::Car(char const*, char const*, char const*, int, int, double) (Car.cpp:29)
==86467== by 0x401229: main (main_prof.cpp:23)
==86467==
==86467== 6 bytes in 1 blocks are definitely lost in loss record 5 of 6
==86467== at 0x4C2AC38: operator new[](unsigned long) (vg_replace_malloc.c:433)
==86467== by 0x400C2C: sdds::Car::Car(char const*, char const*, char const*, int, int, double) (Car.cpp:27)
==86467== by 0x40126D: main (main_prof.cpp:23)
==86467==
==86467== 6 bytes in 1 blocks are definitely lost in loss record 6 of 6
==86467== at 0x4C2AC38: operator new[](unsigned long) (vg_replace_malloc.c:433)
==86467== by 0x400C98: sdds::Car::Car(char const*, char const*, char const*, int, int, double) (Car.cpp:31)
==86467== by 0x40126D: main (main_prof.cpp:23)
==86467==
==86467== LEAK SUMMARY:
==86467== definitely lost: 32 bytes in 6 blocks
==86467== indirectly lost: 0 bytes in 0 blocks
==86467== possibly lost: 0 bytes in 0 blocks
==86467== still reachable: 0 bytes in 0 blocks
==86467== suppressed: 0 bytes in 0 blocks
==86467==
==86467== ERROR SUMMARY: 6 errors from 6 contexts (suppressed: 0 from 0)
So this is the memory leak issue I am facing can anyone please help me to solve this
1 answers
solution1
1 2022-06-08 19:34:25
When you call setInfo() you don't delete the strings you allocated in the constructor and the variables are assigned new values, the previous pointers are dangling and cannot be deleted - hence the memory leak
In cpp I would suggest to use
std::string, there is no need in allocating raw pointers in that case - and these memory leaks are a good lesson why.Code review wise - if you do decide to use pointers, the destructor and
resetInfo()have much in common and you can useresetInfo()as part of the destructor.
Good luck!
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