assigning a string to a char *argv[]

[csharp100]

I have a program that USED to take command line arguments and now I am trying to add a user menu instead.

    int menuChoice;
    string start;
    string end;
    string fileName;
    ifstream in;

 switch (menuChoice) {
        case 1:
            cout<<"Enter the starting city: ";
            cin>>start;
            cout<<"\nEnter the ending city: ";
            cin>>end;
            cout<<"\nEnter the name of the file: ";
            cin>> fileName;

        break;

In the old code I had this:

char * StartCity = argv[1];
char * EndCity = argv[2];
in.open(argv[3],ios::in)

I know this:

char * StartCity = start //start is a string in the menu
char * EndCity = end //end is a string in the menu

Does not work.

I think this does

file.open (fileName.c_str(), ios::in);

The reason is throughout the program I test the argv's like:

bool ArgCheck = TestArgs(argv[1],cities,st);
      if(!ArgCheck) {
         throw MyException("Start city not found in map file.");
      }

and I also have functions that use char * like:

void StackCities(char * StartCity, char * EndCity,...); //<---part of a function

Can someone show me how I can assign those string names in the menu to the argv[1], argv[2] and argv[3]?

[jimblumberg]

You are mixing C-strings with std::strings, I recommend you stick with the std::strings. Convert the StartCity and EndCity to std::strings instead of the C-strings. If you don't want to change your other functions then use the std::string.c_str() member function when you need to pass a C-string into your function. However I suggest that you also consider changing the other functions to use std::strings as well.

bool ArgCheck = TestArgs(StartCity.c_str(), cities, st);

Jim

[csharp100]

You are mixing C-strings with std::strings, I recommend you stick with the std::strings. Convert the StartCity and EndCity to std::strings instead of the C-strings. If you don't want to change your other functions then use the std::string.c_str() member function when you need to pass a C-string into your function. However I suggest that you also consider changing the other functions to use std::strings as well.

bool ArgCheck = TestArgs(StartCity.c_str(), cities, st);

Jim

Can you show me an example of std::string.c_str()? I have a bunch of functions and that would really be a pain.

[jimblumberg]

Look at the code I posted, that is an example of using the std::string.c_str().

It may be a pain to convert your functions to std::string but the pain will probably be worth the effort.


Jim

[csharp100]

Look at the code I posted, that is an example of using the std::string.c_str().

It may be a pain to convert your functions to std::string but the pain will probably be worth the effort.


Jim

So anywhere I have a char * I am to replace that with the example yo ushowed me with the exception of the variable name?

[jimblumberg]

So anywhere I have a char * I am to replace that with the example

Only if the char* is pointing to a C-string. See this link for std::string.c_str().


Jim