Anyone decent with C++ (Need basic help!)

renixian

United States50 Posts

October 07 2010 12:40 GMT

I'm trying to do a code that the program "guesses" your number between 1-100 then lists the number of attempts it took to achieve that. But I can't seem to get my coding to work, I'm quite new to this so I'm sure I made multiple mistakes but I can't see them at the moment nor does VStudios tell me :[

The major issue I'm currently having is that it's not changing the variable guess to the estimate, keep thinking that it's still 100+1/2 so constantly outputs 50. I'm sure I'm missing a way to change the constant within the switch or I'm missing a loop but I don't see it right now :[

Any help/advice would be greatly appreciated!

The code is as follows

#include <iostream>
using namespace std;

int main()
{
int low = 1, high = 100;
bool correct = false;
int guess = (high + low) / 2;
int response;
int counter=1;

cout << "Think of a number between 1 and 100\n";
cout << "tell me if I'm too high(1), too low(2), or if I'm correct(3)\n";

do
{
cout << "My guess is " << guess << " ,is it..\n";
cout << "1 - High?\n";
cout << "2 - Low?\n";
cout << "3 - Correct?\n";
cin >> response;

for(counter = 1; counter >=100; counter++);

switch(response)
{
case 1:
high = guess - 1;
break;
case 2:
low = guess + 1;
break;
case 3:
correct = true;
break;
default:
cout << "Invalid response\n";
continue;
}
}

while(!correct);

cout << "Your number is " << guess << "this was achieved in " << counter << "tries.\n";
return 0;
}

Random()

Kyrgyz Republic1462 Posts

October 07 2010 12:48 GMT

You change high and low but you never change guess.

Try moving "guess = (high + low) / 2" line inside the do block (but keep the declaration outside).

renixian

United States50 Posts

October 07 2010 12:59 GMT

Thank you! That solved my problem of the value not changing! \o/

Inkarnate

Canada840 Posts

October 07 2010 13:00 GMT

Yeah, when you initially declare the variables, thats only the value they are created with. Every time you want to update the value you need to run that line of code again.

An easier way to do the problem would be to get rid of high and low altogether. Since you know the value is between 1 and 100 already you can just start guess at 50 and then add or subtract 1 depending on how the position. This uses less variables and is generally more efficient.

renixian

United States50 Posts

October 07 2010 13:11 GMT

Yeah I was thinking of doing that, but I felt it would be annoying for the end-user to sit there and hit lower 49 times til it finally gets to 1.

Now I'm having a run-time issue :[ I'll ask a friend more in-depth tomorrow. Thanks for your help already though!

Navane

Netherlands2749 Posts

October 07 2010 13:18 GMT

You are not supposed to just add or substract 1. You are supposed to go from 50 to 25, to 34 to 29 to 27 to 28; go to halfway. That way you reach your destination much quicker.

Inkarnate

Canada840 Posts

October 07 2010 13:27 GMT

See above, efficiency is a big deal especially when dealing with large sorting algorithms. Pretty much the logical approach to the question is:

Guess 50, find out if higher or lower.
Guess 25 or 75 depending, find out if higher or lower.

So and an so forth, halving the possible remaining numbers. Even though this may be inefficient for a range of 100, a correctly coded program can accept any parameters (range > 100).

I'll let you figure out how to code it

tofucake

Hyrule19178 Posts

October 07 2010 15:32 GMT

first, code tags are awesome.

second,

#include <iostream.h>

int main()
{
	int guess = 50;
	int in = 0;
	int n = 3;
	bool cond = false;
	
	while(cond == false)
	{
		cout << "Enter a number between 1 and 100: ";
		cin >> in;
		cond = in < 1 || in > 100 ? false : true;
	}
	
	while(in != guess)
	{
		cout << "Is your number less than [0], greater than [1], or equal to [2] " << guess << "?  ";
		cin >> n;
		if(n == 2) break;
		if(n == 0) guess /= 2;
		if(n == 1) guess += (guess / 2);
	}
	return 0;
}

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