Question

Program to print

*
**
***
****

C++..class 11​

Answer 1

$\underline{\underline{\huge{\textbf{Pattern\: Printing\: program\: in\: C++}}}}$

/* C++ program to print the given pattern */

include <iostream>
using namespace std;
int main()
{
int n;
cout << "Enter number of rows: ";
cin >> n;
for(int r = 1; r <= n; r++)
{
for(int c = 1; c <= r; c++)
{
cout << "*";
}
cout << "\n";
}
return 0;
}

$\underline{\LARGE{\textsf{Explanation :}}}$

$\begin{tabular}{|c||c|c|c|c|}\cline{1-2}Row-1&*\\\cline{1-3}Row-2&*&*\\\cline{1-4}Row-3&*&*&*\\\cline{1-5}Row-4&*&*&*&*\\\cline{1-5}\end{tabular}$

$\sf\textsf{First the logic with which the pattern exists is to be noted.}$

In each row, asterisks are to be printed and the number of asterisks in each row is equal to corresponding row number.

$\sf\textsf{If there is a need of user interaction,}\\\sf\textsf{then the no. of rows is taken as \rm in put from user.}$

$\sf\textsf{Here, the variable that stores this value is considered}\\\sf\textsf{as 'n'. (which is declared in the function main)}$

$\sf\textsf{In this case, n = 4, as there are 4 rows}$

$\sf\textsf{Summarizing the observed conditions}\\\sf\textsf{of the pattern:}$

$\sf\textsf{1. Asterisks are to be printed in each row}\\\sf\textsf{till the Last row (Which is given by}\\\sf\textsf{the Number of Rows (n))}$

$\sf\textsf{2. No. of asterisks in each row is equal to}\\\sf\textsf{the the Row Number.}$

$\sf\textsf{3. The printing line has to be changed to new line}\\\sf\textsf{when No. of Asterisks are printed as per [2].}$

$\sf\textsf{So, there is a need of 2 variables,}\\\sf\textsf{1. To track the Row}\\\sf\textsf{2. To track the column}$

$\sf\textsf{Here, r is row control and c is column control}$

$\sf\textsf{(which are declared inside respective for \rm lo op )}$

$\sf\textsf{To implement Condition -1, a for \rm lo op is used}\\\sf\textsf{with variable r initialised to 1 and incremented}\\\sf\textsf{after evaluation of Statements inside it with condition r < =n}$

$\sf\textsf{To implement condition-2, another for \rm lo op is used}\\\sf\textsf{with variable c initialised to 1 and incremented}\\\sf\textsf{after evaluation of Statements inside it with condition c < =r }$

$\sf\textsf{Note that the condition -2 is implemented in according}\\\sf\textsf{ to condition-1, so the for \rm lo ops will be nested.}$

$\sf\textsf{When the condition inside second for \rm lo op (c < =r)}\\\sf\textsf{evaluates to false, the printing line is changed}\\\mathsf{using\: cout\: << " \backslash n " ;}$

$\underline{\textbf{Note:}}$

$\sf\textsf{In case, if space is needed after each asterisk,}\\\sf\textsf{line-12 can be changed to cout << "* ";}$

$\sf\textsf{If there is no need of user interaction in}\\ \sf \textsf{the program, then the no. of rows can directly}\\\sf\textsf{assigned to n at the time of declaration (in line-5)}\\\sf\textsf{and line- 6 \& 7 can be excluded}$

Answer 2

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