How to write nested for loop in C++?

 In C++, a nested loop is a loop inside another loop. Nested loops are useful when you need to perform repetitive tasks on multi-dimensional data structures like arrays, matrices, or tables. The basic syntax of a nested loop in C++ is as follows:

for (int i = 0; i < N; i++) {
   for (int j = 0; j < M; j++) {
      // code to be executed
   }
}

In this example, we have a for loop nested inside another for loop. The outer loop iterates over a range of values for the variable i, and the inner loop iterates over a range of values for the variable j. The code inside the inner loop is executed for every combination of i and j.

Here's an example of a nested loop in C++ that prints a multiplication table:

#include <iostream>

using namespace std;

int main() {
   for (int i = 1; i <= 10; i++) {
      for (int j = 1; j <= 10; j++) {
         cout << i * j << "\t";
      }
      cout << endl;
   }
   return 0;
}

In this example, the outer loop iterates over the values 1 to 10 for the variable i, and the inner loop iterates over the values 1 to 10 for the variable j. The code inside the inner loop prints the product of i and j, separated by a tab character. After the inner loop completes for each value of i, a new line is printed using the endl command.

The output of this program will be:

1	2	3	4	5	6	7	8	9	10	
2	4	6	8	10	12	14	16	18	20	
3	6	9	12	15	18	21	24	27	30	
4	8	12	16	20	24	28	32	36	40	
5	10	15	20	25	30	35	40	45	50	
6	12	18	24	30	36	42	48	54	60	
7	14	21	28	35	42	49	56	63	70	
8	16	24	32	40	48	56	64	72	80	
9	18	27	36	45	54	63	72	81	90	
10	20	30	40	50	60	70	80	90	100