hello.c | Nest

/**
 * File:        hello.c
 * Author:      Risto Heinsar
 * Created:     01.09.2014
 * Edited:      10.08.2023
 *
 * Description: This is an extended "Hello, world!" sample
 *              introducing you to variable declarations and
 *              input and output commands
 */

#include <stdio.h> // includes the standard input-output library (printf, scanf)

int main(void) // The program always starts from the main function
{
    char userName[21];      // Declare variable for text, 20 + 1 characters
    int year, age;          // Declare 2 variables for integers
    
    printf("Hello!\n");     // Print text to the terminal. \n - newline
    
    printf("What's Your name?\n");
    scanf("%s", userName);       // Reads input from user, %s - format for text
                                 // Stores it in the varibable userName
    
    // Printing text, places contents of userName variable to placeholder %s
    printf("Hello, %s. Nice to meet You!\n", userName);

    printf("When were You born?\n");
    scanf("%d", &year); // To read integers, format specifier %d is used
                        // Ampersand (&) must be placed before the variable name
                        // whenever reading a number (e.g. integer) 
    
    // Calculating the rough estimate of the age
    age = 2023 - year;  // The calculation is always placed on the right of the
                        // assignment operator (=). It will be evaluated.
                        // The result is stored in the variable placed on the
                        // left of the assignment operator.

    printf("%s, You are most likely %d years of age\n", userName, age);

    return 0; // The program finished successfully. 0 indicates success.
}

/**

* File: hello.c

* Author: Risto Heinsar

* Created: 01.09.2014

* Edited: 10.08.2023

* Description: This is an extended "Hello, world!" sample

* introducing you to variable declarations and

* input and output commands

#include <stdio.h> // includes the standard input-output library (printf, scanf)

int main(void) // The program always starts from the main function

{

char userName[21]; // Declare variable for text, 20 + 1 characters

int year, age; // Declare 2 variables for integers

printf("Hello!\n"); // Print text to the terminal. \n - newline

printf("What's Your name?\n");

scanf("%s", userName); // Reads input from user, %s - format for text

// Stores it in the varibable userName

// Printing text, places contents of userName variable to placeholder %s

printf("Hello, %s. Nice to meet You!\n", userName);

printf("When were You born?\n");

scanf("%d", &year); // To read integers, format specifier %d is used

// Ampersand (&) must be placed before the variable name

// whenever reading a number (e.g. integer)

// Calculating the rough estimate of the age

age = 2023 - year; // The calculation is always placed on the right of the

// assignment operator (=). It will be evaluated.

// The result is stored in the variable placed on the

// left of the assignment operator.

printf("%s, You are most likely %d years of age\n", userName, age);

return 0; // The program finished successfully. 0 indicates success.

}

It’s important to note that besides the code, many important elements from the style guide play a role in here. To be more precise, parts like indenting, commenting, dashes, variable naming convention and sticking with the line length limit are important.

Some common errors when starting to code C

Missing semicolon after a statement
Mistyping the library name (studio instead of stdio)
Forgetting to include newline characters
Including a newline in the scanf format (“%d\n”) – typically you don’t want it there
Missing & (ampersand) when reading a single integer, float or character
Mixing upper and lower case characters – C is case sensitive

The program converted into UML