Memory management issue with string in CPP

Question

I am trying to seperate strings that are filled with ' ' and store that in array. For that I wrote code,

string* componentsOfStringSeperatedBystring(string originalString, string stringCompare){

string *arryOfStrings=NULL;

string *tempArrayString = NULL;
for (int i=0; i<originalString.length(); i++) {


    size_t position = originalString.find(stringCompare);
    cout << "\nposition" <<position;

    if (position == originalString.npos) {

        break;
    }
    size_t subStringLength = originalString.length() - position;

    cout << "\nsubStringLength" <<subStringLength;
    string subString = originalString.substr(0,position);

    cout << "\nsubString" <<subString;

    tempArrayString = (string*)realloc(arryOfStrings, (i+1)*sizeof(string));

    cout << "\n i \t" <<i;
    if (tempArrayString != NULL) {

        arryOfStrings = tempArrayString;
        arryOfStrings[i] = subString;
    }


    cout << "\narryOfStrings" <<arryOfStrings;
    originalString = originalString.substr(position+1,subStringLength);
}

return arryOfStrings;
}

I am getting crashed on line "arryOfStrings[i] = subString;", If I simply allocate enough space first, and then without reallocating, I am not getting crashed.

The first thing to do is to use std::vector instead of that pointer array you have going on there. — Qaz
– Qaz, Commented Dec 25, 2012 at 11:01
+1 @chris why would some one use pointers to string and realloc… — Tristram Gräbener
– Tristram Gräbener, Commented Dec 25, 2012 at 11:02
@rakeshNS how do you mean seperate strings that are filled with ' ' ? Do you mean separate string by ' ' ? — billz
– billz, Commented Dec 25, 2012 at 11:08

Tom van der Woerdt · Accepted Answer · 2012-12-25 11:03:21Z

1

Don't use C-style memory management on C++-style objects. Either go fully C-style (use null-terminated char* strings) or go fully C++-style (use std::vector<std::string>).

answered Dec 25, 2012 at 11:03

Tom van der Woerdt

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1 Comment

rakeshNS Over a year ago

I used std::vector<std::string>, and now it is working. Thanks :)

Alok Save · Accepted Answer · 2012-12-25 11:01:32Z

1

You need to use new with std::string not c memory allocation functions.
They do not call constructors for std::string class unlike new. And the constructor for std::string class needs to be called for its proper initialization.

To be honest you shouldn't be using std::string * at all. In doing so You lose all the advantages that were gained in avoiding using char * to begin with. Simply use:

std::vector<std::string>

answered Dec 25, 2012 at 11:01

Alok Save

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