Getting char* array from c++ stringstream ostringstream -

i trying copy ostringstream char* array , hoping can me understanding mistake lies. looked on forum, found things similar , unfortunately still unable property copy ostringstream char*. in short trying copy char* via:

ostringstream bld bld<<"test"<<"is"<<"good" const char * result = bld.str().c_str(); 

the complete code reproduce error below. in code having 2 functions build strings via ostringstream. in makefilepath() function build complete file path (ie /path/file.txt). in add() function, add 2 more char* arrays argument prefix /path/file.txt suffix.

the problem unknown reason me fullfilepath changes prefix /path/file.txt suffix. last 3 lines of code exhibit that.

i spent hours on this, thinking maybe referencing issue or else. however, none attemped worked. ideas how on problem?

thanks!!

#include <iostream> #include <sstream> #include <string>  using std::cout; using std::endl; using std::string;  using std::ostringstream;  const char* add(const char *filename) {     ostringstream bld;     const char *prefix = "prefix";     const char *suffix = "suffix";     bld << prefix << " " << filename << " " << suffix;     string temp = bld.str();     cout << "in add(): \n\t" << temp << endl;     return temp.c_str(); }  const char * makefilepath(const char *path, const char *name, const char *ext =         ".txt") {     ostringstream bld;     bld << path << name << ext;     cout << "makefilepath(), returning: \n\t" << bld.str()<< endl;     string temp = bld.str();     return temp.c_str();  }  int main(int argc, char **argv) {     cout << "=== project start ===" << endl;      const char * filepath = "\\path\\";     const char *filename = "filename";     const char *fullfilepath = makefilepath(filepath, filename);      cout << fullfilepath before calling add():\n\t" << fullfilepath << endl;         const char* str = add(fullfilepath);     cout << fullfilepath after calling add():\n\t" << fullfilepath << endl;      return 1; } 

the short answer need use strdup fix this:

const char* makefilepath(const char *path, const char *name, const char *ext = ".txt") {   ostringstream bld;   bld << path << name << ext;   cout << "makefilepath(), returning: \n\t" << bld.str()<< endl;    return strdup(bld.str().c_str()); } 

this sub-optimal solution have memory leak unless free result of function, plus might return null on occasion cause chaos if don't test it. it'd better return std::string.

if you're using c++, use c++.