C Inputs Outputs

Inputs and Outputs in C Programming Language :

Input Output Function

In C programming, input and output (I/O) operations are essential for interacting with the user. The standard input device is typically the keyboard, and the standard output device is usually the screen. The C Standard Library provides functions to perform I/O operations, primarily through the stdio.h header file.

Output In C :

Output in C refers to the process of displaying or writing data to an external destination, typically to the screen (stdout) or a file.

Standard Output Function : 

printf :

To print the data to standard output , you can use the "printf" function. The syntax is as follows :

Syntax :

printf("format_string", expression1, expression2,...);

NOTE: 

format_string: This is a string that specifies the format in which you want to display the data.

expression1, expressionn2, : These are the values or expressions you want to print , which should match the format specifiers in the format string.

Example: 

#include <stdio.h>

int main() {
    int num = 2;
    printf("The value of number is %d\n", num);
    return 0;
}Output: 
The value of number is 42

Standard Input Function :

scanf : 

Standard input represents the source from which your program can read, typically the keyboard.
To read the data from standard input , you can use the "scanf"  function. The syntax is as follows :

Syntax : 

scanf("format_specifier", &variable1, &variable2 ...);

 NOTE :

format_specifier: These are the placeholders that specify the type of data you want to read. For examle, %d for integers, %f for floating-point numbers, %c for characters, %s for string, etc.

&variable1, &variable2: These are the variables where the data will be stored after reading.

Example: 

        
#include <stdio.h>

int main() {
    int age;
    printf("Enter your age: ");
    scanf("%d", &age);
    printf("You are %d years old.\n", age);
    return 0;
}
Output: 
Enter your age: 18    //Entered by the user
You are 18 years old.    // After reading the input

getchar() and gets() :

These function are used for reading individual characters or strings from the keyboard. 

Example of getchar() :

#include <stdio.h>

int main() {
    char c;
    printf("Enter a character: ");
    c = getchar();
    printf("You entered: %c\n", c);
    return 0;
}
Output: 
Enter a character: a
You entered: a
    

Example of gets() :

        
#include <stdio.h>

int main() {
    char name[50];
    printf("Enter your name: ");
    gets(name); // Unsafe, use fgets instead.
    printf("Hello, %s!\n", name);
    return 0;
}

NOTE :

• Reads a string from the standard input until a newline character is encountered.

• 'gets' is considered unsafe because it does not perform bounds checking. Use 'fgets' instead.

putchar() :

• Writes a single character to the standard output.

Example of putchar() :

#include <stdio.h>

int main() {
    char c = 'A';
    printf("The character is: ");
    putchar(c);
    putchar('\n');
    return 0;
}

Understanding and using input and output functions in C is crucial for building interactive programs and performing file operations. These functions provide a foundation for reading user input, displaying information, and manipulating files effectively. By mastering these concepts, you can create robust and user-friendly applications that can interact with users and handle data efficiently.