C++ str_replace

#include <iostream>#include <string> using namespace std; string& str_replace(const string &search, const string &replace, string &subject); int main(int argc, char *argv[]){    string str;     //test basic replace    str    ="I have a lovely bunch of cocoa nuts";    cout << str << endl;    cout << str_replace(" ", " ;", str) << endl;     //test removal of spaces    str    ="I have a lovely bunch of cocoa nuts";    cout << str << endl;    cout << str_replace(" ", "", str) << endl;     //this test will generate an infinite loop if not done in 1 pass    str    ="I have a lovely bunch of cocoa nuts";    cout << str << endl;    cout << str_replace(" ", " a", str) << endl;     return 0;} string& str_replace(const string &search, const string &replace, string &subject){    string buffer;     int sealeng = search.length();    int strleng = subject.length();     if (sealeng==0)        return subject;//no change     for(int i=0, j=0; i<strleng; j=0 )    {        while (i+j<strleng && j<sealeng && subject[i+j]==search[j])            j++;        if (j==sealeng)//found 'search'        {            buffer.append(replace);            i+=sealeng;        }        else        {            buffer.append( &subject[i++], 1);        }    }    subject = buffer;    return subject;}