An introduction to Flowcharts

What is a Flowchart?
Flowchart is a graphical representation of an algorithm. Programmers often use it as a program-planning tool to solve a problem. It makes use of symbols which are connected among them to indicate the flow of information and processing.
The process of drawing a flowchart for an algorithm is known as “flowcharting”.

Basic Symbols used in Flowchart Designs

Terminal: The oval symbol indicates Start, Stop and Halt in a program’s logic flow. A pause/halt is generally used in a program logic under some error conditions. Terminal is the first and last symbols in the flowchart.
Input/Output: A parallelogram denotes any function of input/output type. Program instructions that take input from input devices and display output on output devices are indicated with parallelogram in a flowchart.
Processing: A box represents arithmetic instructions. All arithmetic processes such as adding, subtracting, multiplication and division are indicated by action or process symbol.
Decision Diamond symbol represents a decision point. Decision based operations such as yes/no question or true/false are indicated by diamond in flowchart.
Connectors: Whenever flowchart becomes complex or it spreads over more than one page, it is useful to use connectors to avoid any confusions. It is represented by a circle.
Flow lines: Flow lines indicate the exact sequence in which instructions are executed. Arrows represent the direction of flow of control and relationship among different symbols of flowchart.

Example : Draw a flowchart to input two numbers from user and display the largest of two numbers

C

// C program to find largest of two numbers 
  
#include <stdio.h> 
  
int main() 
{ 
    int num1, num2, largest; 
  
    /*Input two numbers*/
    printf("Enter two numbers:\n"); 
    scanf("%d%d", &num1, &num2); 
  
    /*check if a is greater than b*/
    if (num1 > num2) 
        largest = num1; 
    else
        largest = num2; 
  
    /*Print the largest number*/
    printf("%d", largest); 
  
    return 0; 
} 

C++

// C++ program to find largest of two numbers 
#include <iostream> 
using namespace std; 
int main() 
{ 
    int num1, num2, largest; 
  
    /*Input two numbers*/
    cout << "Enter two numbers:\n"; 
    cin >> num1; 
    cin >> num2; 
  
    /*check if a is greater than b*/
    if (num1 > num2) 
        largest = num1; 
    else
        largest = num2; 
  
    /*Print the largest number*/
    cout << largest; 
  
    return 0; 
} 

Java

// Java program to find largest of two numbers 
import java.util.Scanner; 
public class largest { 
    public static void main(String args[]) 
    { 
        int num1, num2, max; 
  
        /*Input two numbers*/
        Scanner sc = new Scanner(System.in); 
        System.out.println("Enter two numbers:"); 
  
        num1 = sc.nextInt(); 
        num2 = sc.nextInt(); 
  
        /*check whether a is greater than b or not*/
        if (num1 > num2) 
            max = num1; 
        else
            max = num2; 
  
        /*Print the largest number*/
        System.out.println(max); 
    } 
} 

C#

// C# program to find largest of two numbers 
using System; 
using System.IO; 
  
class GFG 
{ 
    static public void Main () 
    { 
          
        int num1, num2, max; 
  
        /*Input two numbers*/
        Console.WriteLine("Enter two numbers:"); 
  
        num1 = Convert.ToInt32(Console.ReadLine());  
        num2 = Convert.ToInt32(Console.ReadLine());  
  
        /*check whether a is greater than b or not*/
        if (num1 > num2) 
            max = num1; 
        else
            max = num2; 
  
        /*Print the largest number*/
        Console.WriteLine(max); 
    } 
} 
  
// This code is contributed by NamrataSrivastava1 

Output

Enter two numbers:
10 30

30

References:
Computer Fundamentals by Pradeep K. Sinha and Priti Sinha

My Personal Notes

C

C++

Java

C#

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