Call a c program from C++ and pass arguments -


i have c++ program, , @ point in program need call c program , pass arguments it.

i working in linux env.

the file simpsh compiled c file in same dir. resulting_simpsh_command string data of type --creat --trunc --wronly f1 , far.

when check values recieve in c program, shows instead

void execute_simpsh(string resulting_simpsh_command) {     pid_t pid = fork();      if(pid == -1)         perror("fork failed!");     else if(pid ==0)     {         char* args[256];          string simpsh ="./simpsh";         args [0] = (char*) simpsh.c_str();         string temp_option_holder="";          int nextcommand=1;          for(int i=0;i<resulting_simpsh_command.length();i++)         {             if(resulting_simpsh_command[i] !=' ')             {                 temp_option_holder += resulting_simpsh_command[i];             }             else             {                 cout<<"saving argument: "<<temp_option_holder<<endl;                 args [nextcommand] = (char*) temp_option_holder.c_str();                 temp_option_holder="";                 nextcommand +=1;             }          }           cout<<"command numbers "<<nextcommand<<endl;         args [nextcommand + 1] = null;          if(execvp(args[0],args) == -1)             cout<<"failed open simpsh, maybe didnt compile?"<<endl;         exit(1);     }     else     {         //not important      } }

a lot of args array invalid pointers due (mis)use of c_str.
pointer becomes invalid string's buffer reallocated.
of args pointers point same thing though they're valid.

two options fixing (off top of head):

dynamic allocation:

args[nextcommand] = strdup(temp_option_holder.c_str());

which requires deallocation later.

or, if can live limiting argument length, can use array , avoid memory management (but need worry overflows instead):

char arg_strings[256][argument_length] = {0}; char* args[256] = {0};  // ... assert(temp_option_holder.length() < argument_length); strncpy(arg_strings[nextcommand], temp_option_holder.c_str(), argument_length); args[nextcommand] = arg_strings[nextcommand];

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