How to fix addition/multiplication table errors? - c++

Question

I am having troubles with some of the inputs for my addition/multiplication table, and am hoping to find some help towards fixing this. I will begin by posting what I have for the program.
The code is as follows :
#include <iostream>
using namespace std;
void die() {
cout << "BAD INPUT!" << endl;
exit(1);
}
int main() {
const int ADD = 1;
const int MULTIPLY = 2;
const int MAX_SIZE = 20;
int choice = 0, min = 0, max = 0;
cout << "Choose:\n";
cout << "1. Addition Table\n";
cout << "2. Times Table\n";
cin >> choice;
if (!cin) die();
if (choice != ADD and choice != MULTIPLY) die();
cout << "Please enter the smallest number on the table:\n";
cin >> min;
if (!cin) die();
cout << "Please enter the largest number on the table:\n";
cin >> max;
if (!cin) die();
if (min > max) die();
if (max - min >= MAX_SIZE) die();
if (choice == ADD) {
for (int i = 0; i <= max; i++) {
if (i == 0)
cout << '+';
else
cout << i;
cout << '\t';
for (int j = min; j <= max; j++) {
cout << i + j << '\t';
}
cout << '\n';
}
}
if (choice == MULTIPLY) {
for (int i = min; i <= max; i++) {
if (i == min) {
cout << 'X';
else
cout << i;
cout << '\t';
for (int j = min; j <= max; j++) {
cout << i * j << '\t';
}
cout << '\n';
}
}
}
Now, here are the mistakes that I am getting from this code that I cannot seem to resolve. First, when doing the MUlTIPLY table with min = 1, max = 1, I am getting:
X 1
when I should be getting (I believe)
X 1
1 1
Secondly, while doing the MULTIPLY table with min = 1, max = 12, I am getting:
X 1 2 3 4 ... 12
2 2 4 6 8 ... 24
3 3 6 9 12 ... 36
when I should be getting
X 1 2 3 4 ... 12
1 1 2 3 4 ... 12
2 2 4 6 8 ... 24
3 3 6 9 12 ... 36
And finally, when using the ADD table with min = 21, max = 40, I cannot post all of the code since it is such a mess, but basically the columns/rows are as follows:
+ 21 22 23 24 25 ...
5
1
6
2
7
3
8
When obviously, the code should output the rows and columns to be 21 - 40 evenly. As you can see in the last example, my rows are outputting properly, but somehow my columns are a complete, garbled mess.
I have been sitting and staring at this code for awhile, and can't seem to fix these issues at hand. Can anyone help lead me in the right direction? I really appreciate any help and hints :)

Answer 1

Check this out. Might not be fully optimized, but works
if (choice == ADD) {
cout << '+';
for (int i = min; i <= max; i++) {
cout << '\t' << i;
}
for (int i = min; i <= max; i++) {
cout << '\n' << i << '\t';
for (int j = min; j <= max; j++) {
cout << i + j << '\t';
}
}
}
if (choice == MULTIPLY) {
cout << 'X';
for (int i = min; i <= max; i++) {
cout << '\t' << i;
}
for (int i = min; i <= max; i++) {
cout << '\n' << i << '\t';
for (int j = min; j <= max; j++) {
cout << i * j << '\t';
}
}
}
See output here.

Answer 2

#include <iostream>
#include <iomanip>
#include <cstdio>
void die()
{
std::cout << "BAD INPUT!" << "\n";
exit(1);
}
int main() {
const int ADD = 1;
const int MULTIPLY = 2;
const int MAX_SIZE = 20;
int choice = 0, min = 0, max = 0;
std::cout << "Choose:\n";
std::cout << "1. Addition Table\n";
std::cout << "2. Times Table\n";
std::cin >> choice;
if (!std::cin) die();
if (choice != ADD and choice != MULTIPLY) die();
std::cout << "Please enter the smallest number on the table:\n";
std::cin >> min;
if (!std::cin) die();
std::cout << "Please enter the largest number on the table:\n";
std::cin >> max;
if (!std::cin) die();
if (min > max) die();
if (max - min >= MAX_SIZE) die();
if (choice == ADD) {
for (int i = 0; i <= max; i++) {
if (i == 0)
printf(" +");
else
printf("%3d", i);
printf(" ");
for (int j = min; j <= max; j++) {
printf("%3d ", i + j);
}
printf("\n");
}
}
if (choice == MULTIPLY) {
/* for printing header of the multiplication table */
std::cout << "X\t";
for (int j = min; j <= max; j++) {
std::cout << min * j << "\t";
}
std::cout << "\n";
/* for printing rest of the table */
for (int i = min; i <= max; i++) {
std::cout << i << "\t";
for (int j = min; j <= max; j++) {
std::cout << i * j << '\t';
}
std::cout << '\n';
}
}
}
The crucial mistake in your code for multiplication was that, you were trying to print (max - min + 1) + 1 rows in total, the extra +1 for the header. While your code was printing the first row as header and then starting directly with the second row.
Your code for addition table was correct, but 21 to 40 with tab character in between was too taking too much space for a typical laptop screen, not to say the output won't be pretty.
On my system, the output of tput lines and tput cols was 38 and 144 resp.
which wasn't sufficient for your code.
you can format the output with printf using printf fixed width output.
Considering you are not much familiar with C++, I would like to state that
using the std namespace as default namespace will work for this program, but when you working with larger projects, you should always prefix it.

Answer 3

I haven't enough reputation to add comment
if I were, I was commenting these lines
if (i == min) {
cout << 'X';
else
cout << i;
cout << '\t';