Input and Output

In C programming, you can interact with the user using input and output functions. This means you can ask the user to enter something, and you can show results on the screen.

Output: printf()

We use the printf() function to display messages or variable values.

Example:

printf("Hello, World!\n");
int age = 20;
printf("Your age is: %d\n", age);

Input: scanf()

We use the scanf() function to take input from the user. You need to specify the data type you want to read and use the address-of operator (&).

Example:

int age;
printf("Enter your age: ");
scanf("%d", &age);
printf("You entered: %d\n", age);

Format Specifiers for Input and Output

• %d → for int
• %f → for float
• %lf → for double
• %c → for char
• %s → for string (array of characters)

Reading Multiple Values

You can also read multiple values at once:

int x, y;
printf("Enter two numbers: ");
scanf("%d %d", &x, &y);
printf("You entered: %d and %d\n", x, y);

Example:

#include <stdio.h>

int main() {
    int age;
    float weight;
    char grade;

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

    printf("Enter your weight: ");
    scanf("%f", &weight);

    printf("Enter your grade: ");
    scanf(" %c", &grade); // Note the space before %c

    printf("\n--- Output ---\n");
    printf("Age: %d\n", age);
    printf("Weight: %.1f\n", weight);
    printf("Grade: %c\n", grade);

    return 0;
}