how to use 2D array, 'if' statement and 'for' loop

[sya20]

I have no idea on how to make a 3x3 and 4x4 2D array and also using the 'if' statement. I also need to use 'for' loops for this assignment. My question are what functions do i have to use in order to make the arrays? what are the steps to use 'if' statement and 'for' loops? Here is the assignment question.

Part 1:
Develop a C++ program which asks the user for the choice of either 3x3 or 4x4 2-dimensional array (use 'if' statement). once the choice is made, create either:

>> two 3x3 or arrays (A and B) by assigning random numbers, (0 to 100), to the elements of the arrays or

>> two 4x4 or arrays (C and D) by assigning random numbers, (0 to 100), to the elements of the arrays.

use integer variables.


Part 2:
Continue the C++ program by multiplying the created arrays "A and B" or "C and D" (depending on the user's choice) to produce array E(3x3) or F(4x4).

use 'for' loops.

[jam47]

I'm having trouble in checking the inputs of the user if it is still 1-100...

#include <iostream>
using namespace std;

int main(){
	
	char choice;
	
	cout<<"Enter 'A' =3x3 or 'B' =4x4: ";
	cin>>choice;
	
	
	if (choice=='A' || choice=='a'){
		int arrA[3][3];
		cout<<"You have chose a 3x3 2 dimensional array. \n"<<endl;
		cout<<"Enter 9 random numbers (1-100 only): "<<endl;
		
		for (int a=0; a<3; a++){
			for (int b=0; b<3; b++){
				cin>>arrA[a][b];
			}	
		}
		for (int a=0; a<3; a++){
			for (int b=0; b<3; b++){
				if (arrA[a][b] > 100){
					break;
					cout<<"Enter numbers 1 to 100 only! Follow instructions as stated above. "<<endl;
				}
			}
		}
	}
	else if (choice== 'B' || choice=='b'){
		
	}
	else if (choice != 'A'|| choice != 'a' && choice != 'B' || choice != 'b'){
		cout<<"Choose A/a or B/b only. "<<endl;
	}
}

[sya20]

okay, I know already how to create a 2D array of 3x3 or 4x4 and i also understand how to use for loop but i still don't know how to use the 'if' statement. I tried the code you gave but it only work when I chose A not when I chose B. Then the question said assign random numbers from 0-100, do I actually need to use rand() or srand() ?

[sya20]

This is my new codes. The problem is all the arrays are displayed after i made a choice. How can I fix this? Then how can I label the arrays? I mean, after I run it, the screen will display
"----ArrayA----
3 8 14
13 3 20
7 16 19 " Something like this.

#include <iostream>
using namespace std;

int main()
{
	int choice;
	
	cout << "Enter your choice 3x3 or 4x4 :";
	cin>> choice;
	
	if (choice==3)
		cout<< "You have chose 3x3 array" << endl;
		
			int arrayA[3][3] = {{3,8,14},{13,3,20},{7,16,19}};
		
				for (int i=0; i<3; i++)
				{
					cout<< endl; // to create a new row
					for (int j=0; j<3; j++)
					{
					cout << arrayA[i][j] << " ";
					}	
				}
		
			int arrayB[3][3] = {{16,12,9},{27,12,15},{20,11,40}};
		
				for (int i=0; i<3; i++)
				{
					cout<< endl; // to create a new row
					for (int j=0; j<3; j++)
					{
					cout << arrayB[i][j] << " " ;
					}	
				}
	if (choice==4)
		cout<< "You have chose 4x4 array \n" << endl;
			int arrayC[4][4] = {{2,11,13,5},{6,11,17,33},{2,7,27,10},{10,36,12,8}};
		
				for (int i=0; i<4; i++)
				{
					cout<< endl; // to create a new row
					for (int j=0; j<4; j++)
					{
					cout << arrayC[i][j] << " ";
					}	
				}
				
			int arrayD[4][4] = {{8,4,7,9},{12,1,13,28},{16,5,24,36},{20,15,9,3}};
		
				for (int i=0; i<4; i++)
				{
					cout<< endl; // to create a new row
					for (int j=0; j<4; j++)
					{
					cout << arrayD[i][j] << " ";
					}	
				}
	return 0;
}

[sya20]

can someone check the new codes? what is wrong with the code, why all the arrays are displayed? Please~~

[WakeofMisery]

It almost seems as simple as adding braces ('{}') around your code... Right after the if statements and then again after your for loops.