c++ - Trying to calculate ASCII code sum of my "sir" (string) class -

#include <iostream> #include <string.h>   using namespace std;  class sir{   int lung; //sir lenght   char* sirul;  //pointer first character form sir   public:     sir(const char*);//constructor,for test     ~sir();// destructor     char operator[](int index);     int cod();   };  int sir::cod()     {         sir u=*this;         char* s=sirul;         int i,sum,l=lung;         if (lung=0)             cout<<"ascii code sum 0";         else         {             for(i=0; i<l; i++)                 {                     sum=sum+int(s[i]);                 }         }         return sum;     }  sir::sir(const char* siroriginal) {   int lungime=strlen(siroriginal);//string length   lung = lungime+1;   sirul = new char[lung];   strcpy(sirul,siroriginal); }  sir::~sir(){   delete sirul; }  char sir::operator[](int index){   if(index<lung && index >=0)return sirul[index];//verificare minima, verific daca este in limite   return '\0'; }  int main(){      cout<<"--------------test sir-----------------\n";   sir s("un sir meserias");   char c=s[1];   cout<<c<<"\n";     cout<<s.cod();    } 

when i'm executing program error says "double free or corruption", don't understand causes error. appears after i'm trying calculate ascii code sum of sir(string) cod method, should return integer value.

how can solve problem?

there few problems within code :

1. first :

you have mismatched new[]/delete call here. replace delete sirul delete[] sirul.

2. second :

inside sir::cod, copying object doing

sir u=*this; 

since not using u @ all, should remove line. source of double free. @ end of cod function, u destroyed , internal pointer sirul deleted. since haven't defined copy operator, compiler generate , you'll end sharing pointer across 2 sir instances. when second instance destroyed, sirul deleted again. resulting in error.

3. third :

next, in cod, forgot initialize sum 0. that's why have bad results.

4. fourth :

in cod, doing if (sum = 0). missing == here.