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.

Rules For Creating Flowchart :

A flowchart is a graphical representation of an algorithm.it should follow some rules while creating a flowchart
Rule 1: Flowchart opening statement must be ‘start’ keyword.
Rule 2: Flowchart ending statement must be ‘end’ keyword.
Rule 3: All symbols in the flowchart must be connected with an arrow line.
Rule 4: The decision symbol in the flowchart is associated with the arrow line.

Advantages of Flowchart:

Flowcharts are a better way of communicating the logic of the system.
Flowcharts act as a guide for blueprint during program designed.
Flowcharts help in debugging process.
With the help of flowcharts programs can be easily analyzed.
It provides better documentation.
Flowcharts serve as a good proper documentation.
Easy to trace errors in the software.
Easy to understand.
The flowchart can be reused for inconvenience in the future.
It helps to provide correct logic.

Disadvantages of Flowchart:

It is difficult to draw flowcharts for large and complex programs.
There is no standard to determine the amount of detail.
Difficult to reproduce the flowcharts.
It is very difficult to modify the Flowchart.
Making a flowchart is costly.
Some developer thinks that it is waste of time.
It makes software processes low.
If changes are done in software, then the flowchart must be redrawn

Example : Draw a flowchart to input two numbers from the 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

Python3

# Python program to find largest of two numbers
 
# Input two numbers
num1 = int(input("Enter first number: "))
num2 = int(input("Enter second number: "))
 
# Check whether num1 is greater than num2 or not
if num1 > num2:
    max_num = num1
else:
    max_num = num2
 
# Print the largest number
print("The largest number is:", max_num)