Input and output (I/O) operations

Here’s an example demonstrating different input and output (I/O) operations in C, such as printf, scanf, fgets, and puts. This example takes user input in multiple ways and then displays it.

#include <stdio.h>

int main() {
    int age;
    float height;
    char name[50];

    // Output a message with printf
    printf("Enter your age: ");
    // Input integer with scanf
    scanf("%d", &age);

    printf("Enter your height in meters (e.g., 1.75): ");
    // Input floating-point number with scanf
    scanf("%f", &height);

    // Clear the newline character left by previous scanf
    getchar();

    printf("Enter your name: ");
    // Input string with fgets
    fgets(name, sizeof(name), stdin);

    // Remove the newline character from the end of name if present
    name[strcspn(name, "\n")] = '\0';

    // Output using printf
    printf("\nYour details:\n");
    printf("Name: %s\n", name);
    printf("Age: %d\n", age);
    printf("Height: %.2f meters\n", height);

    // Output using puts
    puts("\nThank you for providing your information!");

    return 0;
}

Explanation of I/O Operations

1. printf for Output

• printf is used to display text and formatted data to the screen.
• Example: printf("Enter your age: "); outputs a prompt for the user.
• Formatting codes like %d, %f, and %s specify the type of data being printed:
  • %d is for integers (e.g., age).
  • %f is for floating-point numbers (e.g., height).
  • %s is for strings (e.g., name).

2. scanf for Input

• scanf reads formatted data from the user.
• Example: scanf("%d", &age); reads an integer and stores it in age.
• Note the & before age and height – scanf requires a pointer to the variable where it will store the input.
• Clearing the Input Buffer: After reading with scanf, getchar() is often used to clear any leftover newline characters, preventing issues with further input (e.g., with fgets).

3. fgets for String Input

• fgets reads a line of text (including spaces) until a newline or the specified character limit.
• Example: fgets(name, sizeof(name), stdin); reads up to 49 characters from user input into name.
• fgets does not require a pointer to the variable but does retain the newline at the end, so we use name[strcspn(name, "\n")] = '\0'; to remove it.

4. puts for Output

• puts is a simpler way to display a string with an automatic newline at the end.
• Example: puts("\nThank you for providing your information!"); outputs the message without needing to specify format specifiers.

Summary of Key I/O Functions

• printf: For formatted output.
• scanf: For formatted input, requiring pointers for variables.
• fgets: For reading strings with spaces; ideal for user names or sentences.
• puts: For printing strings, automatically appending a newline.

This example covers basic I/O functions, showing how printf, scanf, fgets, and puts can be used together to handle a variety of user input and output needs in C.