Strings

**big146** · 06-17-2004

I just noticed something and was wondering why if i write this.

Code:

int main()
{
	cout << "Please enter your first name: ";
	string name;
	cin >> name;
	const string greeting = "Hello, " + name + "!";
	const int pad = 1;
	const int rows = pad * 2 + 3;
	return 0;
}

and I use the following #includes <iostream> and <cstring> I get a crap load of << erros ? but if i change this <cstring> to <string>
It works.

Does <cstring> not work with the << and ? I notice that with the use of <cstring> peeps are using cin.getline. Is that becuase you need to get the entire string including whitespace? and >> wont do that?

**Thantos** · 06-17-2004

<cstring> is the c++ equivlent of <string.h> which deal with null terminated array of characters

<string> controls the string class.

Two very different and seperate files.

**jlou** · 06-17-2004

What Thantos said ...

Plus, you can use cin.getline with C-style null-terminated character arrays if you want to get input without stopping at the first whitespace. Similarly, you can use std::getline with the C++ string class to get input without stopping at the first whitespace. Using >> with either C-style strings or the C++ string class will cause the input to stop at the first whitespace. Note that the getline that works with C++ strings takes different arguments than the one that works with the character arrays. The C++ string version takes the input stream as the first argument (e.g. std::getline(std::cin, ...);), whereas the other version is a member of the input stream class (e.g. std::cin.getline(...);).

**Prelude** · 06-17-2004

>and I use the following #includes <iostream> and <cstring> I get a crap load of << erros ?
Look more carefully at your book's code. Precision is key when writing programs, and a single character can mess you up.

**jlou** · 06-17-2004

Also, you would normally get somewhat obvious errors from using the string class without #include-ing the <string> header. However, in some implementations just #include-ing <iostream> brings in some of the std::string declarations. This causes even more confusion, because the string class seems to work until you try to do certain operations (like using operator>>) that require the <string> header. That is one of the reasons some people think you have to add a .c_str() to output a string to cout -- they just haven't included the proper <string> header.

**big146** · 06-17-2004

Originally Posted by Prelude

>
Look more carefully at your book's code. Precision is key when writing programs, and a single character can mess you up.

I did write the program with <string>,I just wanted to see what it did with <cstring>. I was thinking <cstring> was the updated version of <string>. I did not realize that they are two diff things.

thks for all the replys

P.S. I know there are alot of book reviews out there but i would like to hear from some of you on what would be a good book to learn ths STL.

**Prelude** · 06-17-2004

>i would like to hear from some of you on what would be a good book to learn ths STL
The one you're reading is a good start. Past that, the recommended text is this.

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