As we have learned so far, a string is an array of type char.  So, making the declaration:

char FirstName[8] = "Charles";

would create a "string", which is an array with the seven elements {'C','h','a','r','l','e','s'}, leaving one element left for a terminating NULL character.  We have declared and used pointers to char for strings of indefinite size.  So, making the declaration:

char * LastName = "Germany";

would create an array of characters just large enough (with enough elements) to hold {'G','e','r','m','a','n','y'}, in addition to the terminating NULL character. 

We have written our own String class and used it in many examples, overloading operators such as <<, [], and + to provide methods for copying strings and concatenating them together.  By this, we have seen first hand how strings as arrays of type char are copied and sorted as any other array of data would be - using loops and iteration to pass through elements one by one.  Now that we have seen what goes on behind the scenes, we can move on.  Now that we know what's "under the hood", so to speak, let's drive the car!

Visual C++ offers an excellent string class that includes many functions for sorting, searching and manipulating string data.  In order to use this class, you will need to #include <string.h>.  It is based on a template class named basic_string.  For many reasons, you will also want to use the standard namespace with the string class by declaring using namespace std; at the top of your source file.  This std namespace will be a standard with many of the functions we will use.  If you do this, you should omit the file extension ".h" from your standard include files.  Let's look at some of the useful methods that <string.h> provides:

getline() - gets an entire line of text, including spaces.
get() - takes a line of input. 
ignore() - consumes/flushes characters in the data stream.
toupper() - converts a character to all uppercase.
isdigit() - determines whether string content is numerical.
tolower() - converts a character to all lowercase.
transform() - converts and entire string to uppercase or lowercase.
c_str - converts string objects into normal pointers to char arrays.  Necessary for many operations.
length() - returns the length of a string.
size() - returns the size of a string .
compare() - compares the contents of one string to another.
size() - returns the size of a string (the number of characters).
find() - determines whether a string is contained within a string.
replace() - replaces a portion of a string's contents.
assign() - assigns a portion of one string's contents to another string variable.
concatenate() - adds separate strings together.  Accomplished by overloading the C++ operator +.
insert() - inserts a string into the current string, starting at the specified location.
erase() - erases a string.
substr() - returns a substring of the current string.
begin() - returns a STL iterator specifying the beginning of the string.
end() - returns a STL iterator specifying the end of the string.
find_first_of - search for first occurrence of char that appears in the str argument.
find_first_not_of - search for first occurrence of char that does not appear in the str argument.
find_last_of - search for last occurrence of char that appears in the str argument.
find_last_not_of - search for lastoccurrence of char that does not appear in the str argument.
peek() - looks at but does not extract a character.
putback() - inserts a character into the input stream.

Here are some old tools from the C library that we can use in C++:
strcpy() - Takes 2 char arrays, copies one to another.  Syntax: strcpy(DestinationArray, SourceArray);
strncpy() - Takes 2 char arrays, copies one to another.  Will not overwrite char arrays like strcpy, it will only copy to first null char or until
                it reaches the max number of chars.  Syntax: strncpy(DestinationArray, SourceArray, MAXchars);

To create an instance of a string and assign a value, there are several methods:

string NameFirst = "Charles";    //uses string class's overloaded assignment operator
string NameLast("Germany");      //uses string class's constructor

The string class overloads many of our familiar operators in C++, so you can use +, -, +=, -=, <, >, [ ], and many other operators with strings.

get(), peek() and putback()

Example:

#include <iostream>
using namespace std;

int main()
{
	char ch;
	cout << "Enter a phrase: ";

	while(cin.get(ch))
	{
		if(ch == '!')
		   cin.putback('$');
		else
			cout << ch;
		while(cin.peek() == '#')
			cin.ignore(1,'#');
	}

	return 0;
}

Example:
string str20 = "Hello there";
string str21 = "aeiou";

pos = str20.find_first_of (str21, 0);

cout << pos << endl;     // 1
pos = str20.find_last_not_of ("eHhlort");

cout << pos << endl;     // 5

©2004 C. Germany