Question

Write a program that uses function strcmp to compare two strings input by the user. The program should state whether the first string is less than, equal to or greater than the second string

Short answer

Write a C program using `strcmp` to compare two user-input strings and print the comparison result.

Step-by-step solution

Set Up the Program Structure

Begin by creating a basic structure for the program. Include the necessary header files such as `#include ` and `#include `, which allow for input/output operations and string handling.

Declare Variables

Declare two character arrays to store the input strings. For simplicity, you can define them with a size of 100 characters each, which should be sufficient for most cases.

Get User Input

Use the `printf` function to prompt the user for input and `scanf` to read the two strings from the user. Make sure to provide instructions so the user knows what is expected.

Compare the Strings

Use the `strcmp` function to compare the two strings. This function returns an integer: negative if the first string is less, zero if they are equal, and positive if the first string is greater.

Analyze and Output the Comparison Result

Based on the result from `strcmp`, use an `if`, `else if`, and `else` statement to print whether the first string is less than, equal to, or greater than the second string. Use `printf` to display the appropriate message.

Key concepts

String Comparison

String comparison is an essential part of many programs. It allows you to determine the relationship between two strings based on their lexicographic order. In C++, the strcmp function is a convenient tool for this operation. The function returns:

• A negative value if the first string is lexicographically less than the second.
• Zero if both strings are identical.
• A positive value if the first string is greater than the second.

Understanding the return value of strcmp enables developers to implement logic that reacts differently based on the comparison result. This can be useful in applications such as sorting, searching, or validating user input. It's important to note that string comparison is case-sensitive, meaning `"Hello"` and `"hello"` will not be seen as equal.

User Input Handling

Handling user input effectively is crucial for creating interactive programs. In C++, scanf is one of the functions used to receive input from the user. It is pivotal to guide users with clear prompts using printf, helping them understand what is expected of their input. For example, you can use:

• printf("Enter the first string: ");
• scanf("%s", firstString);

This ensures that users know exactly what information to provide. Furthermore, when using standard input functions like scanf, it is wise to be cautious of buffer overflow, which can occur when the input string exceeds the allocated space. Allocating sufficient memory for the input buffers, such as declaring character arrays of size 100, helps mitigate this risk.

String Handling Functions

String handling functions offer the ability to manipulate and manage strings easily. Aside from strcmp, C++ provides several other string handling functions in the cstring library. These include:

• strcpy: Used to copy one string to another safely.
• strlen: Calculates the length of a string.
• strcat: Concatenates two strings into one.

Using these functions, programmers can perform various operations such as copying, concatenating, and calculating the length of strings. These tools are valuable for managing strings and simplifying code, ensuring that operations on strings are performed efficiently. Familiarity with these functions can significantly enhance the capability to handle strings within a program effectively.