C Input/Output Functions - Complete Guide

#include <stdio.h>

int main() {
    int age = 25;
    float salary = 45000.50;
    char grade = 'A';
    char name[] = "John Doe";
    
    // Basic examples
    printf("Hello, World!\n");
    
    // Integer output
    printf("Age: %d\n", age);
    printf("Age in hex: %x\n", age);
    
    // Floating point output
    printf("Salary: %f\n", salary);
    printf("Salary with 2 decimals: %.2f\n", salary);
    
    // Character output
    printf("Grade: %c\n", grade);
    
    // String output
    printf("Name: %s\n", name);
    
    // Multiple values
    printf("Employee: %s, Age: %d, Salary: $%.2f, Grade: %c\n", 
           name, age, salary, grade);
    
    // Return value demonstration
    int chars_printed = printf("This is a test\n");
    printf("Characters printed: %d\n", chars_printed - 1); // -1 for \n
    
    return 0;
}
                

#include <stdio.h>

int main() {
    int age;
    float height;
    char initial;
    char name[50];
    double salary;
    
    // Reading integer input
    printf("Enter your age: ");
    int result1 = scanf("%d", &age);
    printf("Age: %d, scanf returned: %d\n", age, result1);
    
    // Reading float input
    printf("Enter your height in meters: ");
    int result2 = scanf("%f", &height);
    printf("Height: %.2f meters, scanf returned: %d\n", height, result2);
    
    // Reading character input (note: reads whitespace)
    printf("Enter your initial: ");
    int result3 = scanf(" %c", &initial); // Space before %c ignores whitespace
    printf("Initial: %c, scanf returned: %d\n", initial, result3);
    
    // Reading string input (stops at whitespace)
    printf("Enter your first name: ");
    int result4 = scanf("%s", name);
    printf("Name: %s, scanf returned: %d\n", name, result4);
    
    // Reading multiple values at once
    printf("Enter age and height (separated by space): ");
    int age2;
    float height2;
    int result5 = scanf("%d %f", &age2, &height2);
    printf("Age: %d, Height: %.2f, scanf returned: %d\n", age2, height2, result5);
    
    // Reading double precision
    printf("Enter your salary: ");
    int result6 = scanf("%lf", &salary);
    printf("Salary: %.2lf, scanf returned: %d\n", salary, result6);
    
    // Checking return value for error handling
    int number;
    printf("Enter a number: ");
    if (scanf("%d", &number) == 1) {
        printf("Successfully read: %d\n", number);
    } else {
        printf("Invalid input!\n");
        // Clear input buffer
        while (getchar() != '\n');
    }
    
    return 0;
}
                

#include <stdio.h>

int main() {
    double num1, num2, result;
    char operator;
    
    printf("=== SIMPLE CALCULATOR ===\n");
    
    // Get first number
    printf("Enter first number: ");
    scanf("%lf", &num1);
    
    // Get operator
    printf("Enter operator (+, -, *, /): ");
    scanf(" %c", &operator); // Space before %c to skip newline
    
    // Get second number
    printf("Enter second number: ");
    scanf("%lf", &num2);
    
    // Perform calculation based on operator
    switch(operator) {
        case '+':
            result = num1 + num2;
            printf("\nResult: %.2lf + %.2lf = %.2lf\n", num1, num2, result);
            break;
        case '-':
            result = num1 - num2;
            printf("\nResult: %.2lf - %.2lf = %.2lf\n", num1, num2, result);
            break;
        case '*':
            result = num1 * num2;
            printf("\nResult: %.2lf * %.2lf = %.2lf\n", num1, num2, result);
            break;
        case '/':
            if(num2 != 0) {
                result = num1 / num2;
                printf("\nResult: %.2lf / %.2lf = %.2lf\n", num1, num2, result);
            } else {
                printf("\nError: Division by zero is not allowed!\n");
            }
            break;
        default:
            printf("\nError: Invalid operator!\n");
    }
    
    return 0;
}