C Program Input/Output Operation.

We use a C programming language to communicate with computers to solve problems and once we get our required output we need to show them on the output screen. There might of some cases in which we also take input data from the user itself. Here we are going to understand how to take input and print output of our console screen.

How to take Input/Output in C Programming?

The two important functions printf and scanf are used in the C programming language to perform output and input operations. Let's understand both in detail with examples.

Note: We need to include <stdio.h> header file at the top because both input and output functions are present inside this header file. (alert-success)

printf function.

The printf function is used for formatted output in C. It allows you to print text and values to the console in a specific format.

Example Code:

//C Program to show the working of printf function
#include <stdio.h>

int main() {
    int age = 25;
    float height = 5.9;
    char name[] = "John Doe";

    // Printing variables with format specifiers
    printf("Name: %s\n", name);
    printf("Age: %d\n", age);
    printf("Height: %.2f\n", height);

    return 0;
}

Output:

Name: John Doe
Age: 25
Height: 5.90

In this example, the printf function is used to print the name, age, and height of a person using format specifiers. %s is used for strings, %d for integers, and %.2f for floating-point numbers with two decimal places.

scanf function.

The scanf function is used for formatted input in C. It allows you to read values from the user or a file based on the specified format.

Example Code:

//C Program to take input from user
#include <stdio.h>

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

    // Reading input from the user with format specifiers
    printf("Enter your name: ");
    scanf("%s", name);

    printf("Enter your age: ");
    scanf("%d", &age);

    // Displaying the input values
    printf("Name: %s\n", name);
    printf("Age: %d\n", age);

    return 0;
}

Output:

Enter your name: Algolesson
Enter your age: 5
Name: Algolesson
Age: 5

In this example, the scanf function is used to read the name and age of the user from the console using format specifiers %s and %d, respectively. Note that for reading integers, we need to pass the memory address of the variable using the & (address-of) operator.

Format Specifiers.

We notice that format specifiers are something that we should know. In C programming, format specifiers are used with input/output functions like printf and scanf to specify the data type and format of the variables being printed or read.

List of Format Specifiers in C Program.

%d : Used for integers (decimal format).
%ld : Used for long integers.
%u : Used for unsigned integers.
%f : Used for floating-point numbers (decimal notation).
%lf : Used for double-precision floating-point numbers.
%c : Used for characters.
%s : Used for strings (arrays of characters).
%x : Used for hexadecimal (lowercase letters).
%X : Used for hexadecimal (uppercase letters).
%o : Used for octal numbers.
%% : Used to print a literal % character (escape sequence).

Note: Some format specifiers have variations for different data types, such as %lld for long long integers, %hu for unsigned short integers, etc. (alert-success)