strings in c++

Hi,

This is what I am used to from C.

Code:

---

void func1(char *str);

int main ()
{
      char str[80];
 
      strcpy(str, "Hello Friend");
      func1(str);

      cout << str;

      return 0;
}

void func1(char *str)
{
    while(*str)
    {
          if (isupper(*str))
          *str = tolower(*str);

        else if (islower(*str))
        *str = toupper(*str);

        str++;
      }
}

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Now that I am looking into and learning C++ I think I read somewhere that strings are easier to use. Can anyone assist?

Thanks

There are a lot of tutorials if you google.

To give you the code with strings to convince you that strings are easier in C++:

Code:

---

using namespace std;
void func1(char *str);

int main ()
{
      string str;
 
      str = "Hello friend";
      func1(string);

      cout << str;

      return 0;
}

void func1(string& str)
{
    for(i=0; i<str.size(); ++i)
    {
          if (isupper(str[i]))
          str[i] = tolower(str[i]);

        else if (islower(str[i])
        str[i] = toupper(str[i]);
      }
}

---

Just keep these in mind:
1) You don't have to give a size. Everything is done automatically for you
2) You can use = to copy, don't need strcpy(). You can use + combine strings
3) A lot useful functions http://www.cppreference.com/wiki/string/start

EDIT: (hope nobody realized what I edited :o)

Excellent! Thank you.

I see they are much, much better.

Howver, I have just used one in conjunction with a getchar() immediately after.
It meant that the getchar() didnt.

1. Can anyone know why this happens?
2. What can be done to overcome?

Thanks

didn't what?
getchar() gets a char from the standard input. I don't see what that has to do with strings

1) You use [] with strings as you do with arrays
2) You can make a string into a char* with string.c_str()

Code:

---

void displayText (string str1)
{
        cout << str1;
        getchar ();
        system("cls");
}

---

After I pass in this string and display it. The program doesnt wait for user to press a key.

Its ok. It appears that the getchar() is accepting the ENTER from a previous user input within the main. Thus I have just slipped an fflush(stdin); in before the getchar() is called.

thanks for help

Quote:

---

It appears that the getchar() is accepting the ENTER from a previous user input within the main. Thus I have just slipped an fflush(stdin); in before the getchar() is called.

---

fflush(stdin) is undefined as fflush() works on output streams. Use one of the methods for "flushing" the input stream as described in the FAQ.

Ok. Thanks.

But the FAQ doesn't offer a soln, just:

"So, if the file stream is for input use, as stdin is, the behaviour is undefined, therefore it is not acceptable to use fflush() for clearing keyboard input.
As usual, there are some exceptions, check your compiler's documentation to see if it has a (non-portable) method for flushing input. "

Can anyone offer an alternative for fflush?

Try this FAQ: How do I... Flush the input buffer.

Actually, there's a possibly better solution:

Code:

---

std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
std::cin.get(); // for the "pausing" effect that you want

---

You should #include <limits> to std::numeric_limits.

Quote:

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Originally Posted by C_ntua

Code:

---

using namespace std;
void func1(char *str);

---

EDIT: (hope nobody realized what I edited :o)

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One more thing to edit... You forgot to change the prototype to string& also.

Though it's likely a little bit advanced for you, just to show you a tiny bit of what's possible down the road if you continue to explore the language here's an example of one possible solution to your code that demonstrates the use of what is known as a function object and a helper function called transform (in the <algorithm> header)... just to give you an idea of the myriad different ways that this can be done.

Code:

---

#include <string>
#include <iostream>
#include <algorithm>
#include <cctype>

struct flipcase
{
    inline char operator()(char in) const
    {
        if(islower(in)) return toupper(in);
        else return tolower(in);
    }
};

int main()
{
    std::string str("Hello My Friend");

    std::cout << "Before: " << str << std::endl;

    std::transform(str.begin(),str.end(),str.begin(),flipcase());

    std::cout << "After : " << str << std::endl;

    return 0;
}

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Output should be:

Code:

---

Before: Hello My Friend
After : hELLO mY fRIEND

---