Crashing when trying to delete character array

Question

When it gets to the delete portion where test2 needs to delete the String object it crashes. I am not sure why it crashes. It says "Debug Assertion failed!". Am I deleting the dynamically alloacted char array wrong?

strdrv.cpp:

#include <iostream>
#include <stdlib.h>
#include "strdrv.h"

int main() {
test2();
return 0;
}
void test2() {
cout << "2. Testing S2: String one arg (char *) constructor."
    << endl << endl;
csis << "2. Testing S2: String one arg (char *) constructor."
    << endl << endl;
String s2("ABC");
s2.print();
wait();
}

String.cpp:

#include "String.h"
#include <iostream>

using namespace std;
String::String(char* s) {
int sLength = 0;

for (int i = 0; s[i] != '\0'; i++) {
    sLength++;
}

buf = new char[sLength+1];
dynamicallyAlloc = true;
buf = s;

length = sLength;

/*buf[length] = '\0';*/ 
}

String::~String() {
if(dynamicallyAlloc)
    delete []buf;
}

String.h:

#ifndef _STRING_H
#define _STRING_H

#include <iostream>

using namespace std;

class String {
protected:
bool dynamicallyAlloc;
char nullChar;
int length;
char* buf;
void calculateStringLength();


public:
String();
String(char*);
String(char);
String(int);
String(const String&);
String(char, int);
~String();
int getLength() const;
char* getString() const;
String& operator=(const String&);
String& operator=(const char*);
String& operator+=(const String&);
String operator+() const;
char& operator[](int);
String& operator++();
String& operator--();
String operator++(int);
String operator--(int);
String substr(int, int);
void print();
friend String operator+(const String&, const String&);
friend String operator+(const String&, const char*);
friend String operator+(const char*, const String&);
friend String operator+(const String&, char);
friend String operator+(char, const String&);
friend char* operator+(const String&, int);
friend char* operator+(int, const String&);
friend int operator==(const String&, const String&);
friend int operator!=(const String&, const String&);
friend int operator<(const String&, const String&);
friend int operator<=(const String&, const String&);
friend int operator>(const String&, const String&);
friend int operator>=(const String&, const String&);
friend ostream& operator<<(ostream& os, const String& s1);
};

#endif

After allocating buf, you assign s to it. So you leak the allocated buffer and instead have buf point to the string that was passed to the constructor. At destruction time, you attempt to delete that string. So instead of buf = s;, I guess you want something like strcpy(buf,s);. Of course, using std::string would be much safer. — jogojapan
– jogojapan, Commented Jul 25, 2013 at 1:55
I've voted to put this question on hold, as the code example is far too complicated to be a minimal code example. — jogojapan
– jogojapan, Commented Jul 25, 2013 at 1:57
You have way too many overloads. Let the constructors do some work. — Qaz
– Qaz, Commented Jul 25, 2013 at 1:59

chux · Accepted Answer · 2013-07-25 01:57:50Z

4

To copy the array contents, do not copy the pointer, Instead of

buf = s;

you want copy the contents

memcpy(buf,s, sLength+1);

This preserves the buf you have allocated for later deletion.

answered Jul 25, 2013 at 1:57

chux

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1 Comment

chux Over a year ago

Also recommend changing sLength and i to type size_t.

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