1..How do you input or output a C-style string? What kinds of tools are availabl
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Question
1..How do you input or output a C-style string?
What kinds of tools are available to work with C-style strings?
Show some examples of using those tools!
2.Discuss how C style strings are different from string variables.
3..The cstring library contains functions for copying one C string to another, for getting the length of a C string, and for comparing two C strings.
Can you discuss few of those functions --- cite some examples.
4.Please discuss the methods provided by the string data type and how to use them.
Make sure to include example code demonstrating the use of these functions.
Explanation / Answer
In C++ there are two types of strings, C-style strings, and C++-style strings. This lesson will discuss C-style strings. C-style strings are really arrays, but there are some different functions that are used for strings, like adding to strings, finding the length of strings, and also of checking to see if strings match. The definition of a string would be anything that contains more than one character strung together. For example, "This" is a string. However, single characters will not be strings, though they can be used as strings.
1.
Strings are useful for holding all types of long input. If you want the user to input his or her name, you must use a string. Using scanf() to input a string works, but it will terminate the string after it reads the first space, and moreover, because scanf doesn't know how big the array is, it can lead to "buffer overflows" when the user inputs a string that is longer than the size of the string (which acts as an input "buffer").
There are several approaches to handling this problem, but probably the simplest and safest is to use the fgets function, which is declared in stdio.h.
The prototype for the fgets function is:
char *fgets (char *str, int size, FILE* file);
There are a few new things here. First of all, let's clear up the questions about that funky FILE* pointer. The reason this exists is because fgets is supposed to be able to read from any file on disk, not just from the user's keyboard (or other "standard input" device). For the time being, whenever we call fgets, we'll just pass in a variable called stdin, defined in stdio.h, which refers to "standard input". This effectively tells the program to read from the keyboard. The other two arguments to fgets, str and size, are simply the place to store the data read from the input and the size of the char*, str. Finally, fgets returns str whenever it successfully read from the input.
When fgets actually reads input from the user, it will read up to size - 1 characters and then place the null terminator after the last character it read. fgets will read input until it either has no more room to store the data or until the user hits enter. Notice that fgets may fill up the entire space allocated for str, but it will never return a non-null terminated string to you.
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