C++: How to print a multiplication table using nested loop? - c++

Question

I am running a program in c++ which prints the multiplication table from 1 to 40 but it starts from 13*10=130 to 40 so whats the reason behind this?

Answer 1

Below is the formatted version of the code you posted:
#include<iostream>
using namespace std;
int main() {
for (int i = 1; i <= 40; i++) {
for (int j = 1; j <= 10; j++) {
cout << i << " * " << j << " = " << i*j << endl;
}
cout << endl;
}
return 0;
}
It starts printing at 13 * 10. What's the reason for this?
Notably, we can see the variables of both loops (i and j) are initialized to 1 when the loop starts. Because of this, you would be right in expecting the first loop-through to print 1 * 1 = 1.
This suggests, as PRIME has pointed out, that the environment (such as the Windows Console) that you are printing to may not have a large enough buffer to store and display the 440 lines of output the program will try to print.
How can I get around this?
You can try re-sizing your printing environment's internal buffer (if it allows) to allow for 440 lines of print. In MS-DOS, for example, you can manually change this by right-clicking the title-bar, going into Properties, then the Layout tab, and changing the Screen Buffer width and height to values that suit.
Alternatively, you could conserve print-space by replacing endl statements with regular spaces, a la:
for (int i = 1; i <= 40; i++) {
for (int j = 1; j <= 10; j++)
cout << i << " * " << j << " = " << i*j << ' ';
}
You also have the option of outputting to a file instead of your current printing environment:
#include <fstream>
using namespace std;
int main() {
ofstream Output("Output.txt"); //Creates a file "Output.txt"
if (Output.is_open()) { //If the file is open, proceeed
for (int i = 1; i <= 40; i++) {
for (int j = 1; j <= 10; j++)
Output << i << " * " << j << " = " << i*j << '\n';
Output << '\n'; //^^^Write multiplication table to the file
}
}
return 0;
}