INPUT & OUTPUT

🖰 C-INPUT & C-OUTPUT 💻

Input means to provide the program with some data to be used in the program and Output means to display data on-screen or write the data to a printer or a file.

C programming language provides many built-in functions to read any given input and to display data on the screen when there is a need to output the result.

In this tutorial, we will learn about such functions, which can be used in our program to take input from the user and to output the result on the screen.

💻C-OUTPUT💻

In C programming, printf() is one of the main output function. The function sends formatted output to the screen. For example,

Example 1: C Output

#include <stdio.h> int main() { // Displays the string inside quotations printf("C Programming"); return 0; }

Output

C Programming

Example 2: Integer Output

#include <stdio.h> int main() { int testInteger = 5; printf("Number = %d", testInteger); return 0; }

Output

Number = 5

We use %d format specifier to print int types. Here, the %d inside the quotations will be replaced by the value of testInteger.

Example 3: float and double Output

#include <stdio.h> int main() { float number1 = 13.5; double number2 = 12.4; printf("number1 = %f\n", number1); printf("number2 = %lf", number2); return 0; }

Output

number1 = 13.500000 number2 = 12.400000
\
To print float, we use %f format specifier. Similarly, we use %lf to print double values.

Example 4: Print Characters

#include <stdio.h> int main() { char chr = 'a'; printf("character = %c", chr); return 0; }

Output

character = a

To print char, we use %c format specifier.

🖰 C-INPUT 🖰

In C programming, scanf() is one of the commonly used function to take input from the user. The scanf() function reads formatted input from the standard input such as keyboards.

Example 5: Integer Input/Output

#include <stdio.h> int main() { int testInteger; printf("Enter an integer: "); scanf("%d", &testInteger); printf("Number = %d",testInteger); return 0; }

Output

Enter an integer: 4 Number = 4

Here, we have used %d format specifier inside the scanf() function to take int input from the user. When the user enters an integer, it is stored in the testInteger variable.

Example 6: Float and Double Input/Output

#include <stdio.h> int main() { float num1; double num2; printf("Enter a number: "); scanf("%f", &num1); printf("Enter another number: "); scanf("%lf", &num2); printf("num1 = %f\n", num1); printf("num2 = %lf", num2); return 0; }

Output

Enter a number: 12.523 Enter another number: 10.2 num1 = 12.523000 num2 = 10.200000

We use %f and %lf format specifier for float and double respectively.

Example 7: C Character I/O

#include <stdio.h> int main() { char chr; printf("Enter a character: "); scanf("%c",&chr); printf("You entered %c.", chr); return 0; }

Output

Enter a character: g You entered g

When a character is entered by the user in the above program, the character itself is not stored. Instead, an integer value (ASCII value) is stored.

And when we display that value using %c text format, the entered character is displayed. If we use %d to display the character, it's ASCII value is printed.

Example 8: ASCII Value

#include <stdio.h> int main() { char chr; printf("Enter a character: "); scanf("%c", &chr); // When %c is used, a character is displayed printf("You entered %c.\n",chr); // When %d is used, ASCII value is displayed printf("ASCII value is %d.", chr); return 0; }

Output

Enter a character: g You entered g. ASCII value is 103.

I/O Multiple Values

Here's how you can take multiple inputs from the user and display them.

#include <stdio.h> int main() { int a; float b; printf("Enter integer and then a float: "); // Taking multiple inputs scanf("%d%f", &a, &b); printf("You entered %d and %f", a, b); return 0; }

Output

Enter integer and then a float: -3 3.4 You entered -3 and 3.400000