Exercise 5.2

[Alistair]

How did I do?

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{

    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    int n, triangularNumber, rem;
    
    triangularNumber = 0;
    
    NSLog (@"TABLE OF TRIANGULAR NUMBERS");
    NSLog (@"N  SUM FROM 1 TO N");
    NSLog (@"------------------");
    
    for ( n = 1; n <= 50; ++n)
    {
        rem = n % 5;
        while ( rem == 0) 
        {
            triangularNumber = n * (n +1) / 2;
            NSLog (@"%2i       %i", n, triangularNumber);
            rem = 1;
        }
    }
    [pool drain];
    return 0;
}

[tuhinbhatt]

This might Me Be Silly Question----

But in the solution

 
            triangularNumber = n * (n +1) / 2; 
            NSLog (@"%2i       %i", n, triangularNumber); 
            rem = 1; 

Why rem=1 statement has to be used (I know if we dont use it results in infinite loop)

[skochan]

You don't know as of Chapter 5 about "if" statements, but that's what should be used instead of the while.  Better yet, why not have the for loop count  by 5 instead of by 1?

Cheers,

Steve

[badBandit]

You don't know as of Chapter 5 about "if" statements, but that's what should be used instead of the while.  Better yet, why not have the for loop count  by 5 instead of by 1?

Cheers,

Steve

Hi Steve!

That's exactly what I was trying to do with this:

Code: (Objective-C)

for (n = 5; n <= 50; n + 5) {

But that gave me a warning and an infinite loop where the n + 5 wasn't being used. So my final code went like this:

Code: (Objective-C)

// Program to calculate a table of every 5th triangular numbers

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{
    
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    int n, triangularNumber;
    
    NSLog(@"TABLE OF TRIANGULAR NUMBERS");
    NSLog(@"      n n (n + 1) / 2");
    NSLog(@"     -- -------------");
    
    triangularNumber = 0;
    
    for (n = 5; n <= 50; n = (n + 5)) {
        triangularNumber = n * (n + 1) / 2;
        NSLog(@"     %2i          %i", n, triangularNumber);
        
    }
    
    [pool drain];
    return 0;
}