Re: Suggested method for returning a string from a C program?

DFS <nospam@dfs.com> writes:

On 3/19/2025 1:27 AM, Tim Rentsch wrote:
>

DFS <nospam@dfs.com> writes:
>

On 3/18/2025 11:07 PM, Tim Rentsch wrote:
>
>

Have you thought about how large the value of 'n' can
become inside the while() loop?

>
I was too smug in my first reply.  [...]

>
Yes, I knew that already.  Did you think I asked the question
without having first investigated the problem?

>
I wouldn't presume.
>
Did you investigate first?

Of course.

I just now did:
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gcc on Kali Linux (in Windows WSL)
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run it:  $ ./weird start stop
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$time ./weird 1 1000000
<1000000 lines will be output>
max n = 56991483520 reached at input = 704511
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real    0m5.792s
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>
>
code
-----------------------------------------------------------------
// If n is even, divide it by two.
// If n is odd, multiply it by three and add one.
// Repeat until n is one.
// example:  the sequence for n=3 is  3 10 5 16 8 4 2 1
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#include <stdio.h>
#include <stdlib.h>
>
int main(int argc, char *argv[])
{
int steps, input;
int startN = atoi(argv[1]);
int stopN  = atoi(argv[2]);
int64_t n = 0, max = 0, thismax = 0;
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for (int i = startN; i <= stopN; i++) {
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        n = i;
        steps = 1;
        thismax = n;
        while(1) {
>
            if((n % 2) == 0)
                {n /= 2;}
            else
                {n = (n * 3) + 1;}
>
            if (n > max)     {max = n; input = i;}
            if (n > thismax) {thismax = n;}
            steps++;
>
            if (i == 1) {
                printf("input 1, max n =      1, steps =    1\n");
                break;
            }
>
            if(n == 1) {
                printf("input %d, max n = %6lld, steps = %4d\n",
                    i, thismax, steps);
                break;
            }
        }
>
>
}
printf("\nmax n = %lld reached at input = %d\n", max, input);
return 0;
}
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-----------------------------------------------------------------
>
You'll get compilation warnings about the printf specifier used with
int64_t.

I recommend using unsigned long long rather than int64_t.  After
all, all values reached are guaranteed to be non-negative.  And
there is no confusion or uncertainty about what conversion sequence
to use in the call to printf().