How does `cin` handle input in C and why is `getline()` preferred for reading entire lines?

C Input Stream Behavior with "cin"

When reading input using the "cin" stream in C , it's important to understand how it interacts with various data types. By default, "cin" reads a word at a time, which can lead to unexpected behavior when dealing with character arrays or strings.

In the provided code example, the "input()" method in the "String" class uses "cin >> str;" to read the input string. However, this statement only captures a single word, ignoring any subsequent words in the input. As a result, when the input contains multiple words, such as "steve hawking," only the first word, "steve," is stored in the "str" array.

Solution: Using getline() to Read Complete Lines

To read a complete line of input into a character array, the "getline()" function can be used instead of "cin >>". Here's the updated input method using "getline()":

<code class="c++">void input()
{
    cout << "Enter string :";
    cin.getline(str, sizeof str);
}

"getline()" takes two arguments: a pointer to the destination array and the size of the array. It reads input until a newline character is encountered, effectively capturing the entire line of input.

Additional Considerations

It's worth noting that using character arrays for string manipulation can be cumbersome and error-prone. The C Standard Library provides the "std::string" class, which offers a more robust and type-safe approach to string handling. Instead of using character arrays, the code could be rewritten as:

<code class="c++">#include <iostream>
#include <string>

class String
{
public:
    std::string str;

    void input()
    {
        cout << "Enter string :";
        std::getline(std::cin, str);
    }

    void display()
    {
        std::cout << str;
    }
};</code>

Finally, the use of header files like "iostream.h" and "conio.h" is outdated. Modern C development should use header files such as "iostream" and "conio," respectively.

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