calculating min and max

[Alenik1989]

i just wanna know the logic to find minimum and maximum between some random numbers such as
1 2 3 4 5 6 or 43 7 98 0 89 any ideas?PLS!

[oler1s]

Forget about the code for a moment. Try coming up with an algorithm in plain english that lets you find the minimum and the maximum in a bunch of numbers.

Oh, and we aren't telling you the answer. We'll assist you if you make real attempts at thought and code.

[Alenik1989]

Forget about the code for a moment. Try coming up with an algorithm in plain english that lets you find the minimum and the maximum in a bunch of numbers.

Oh, and we aren't telling you the answer. We'll assist you if you make real attempts at thought and code.

in english language i will compare the numbers like for
1 2 3 4
it will be like
1<2 >>>>>>1min 2max
2<3>>>>>>>2min 3max
3<4>>>>>>>3min 4max
then i will compare mins and maxes together like

1<2>>>>>1min 2max
2<3>>>>>2min 3max
__________
2<3 2min 3max
3<4 3min 4 max
one more time
1<2 1min 2max sooooo min will be 1
____________
3<4 3min 4max sooooo max will be 4

i thought about the code for 3 day can you guys at least give me a hint to statrt with!!!!

[Studlyami]

Interesting way of approaching the problem. In that method you work your way down, but what about a line that had over 100 values to compare. That method would take a while to go through.

What are you really interested in? minimum and maximum. Think about that, you only want to know minimum and maximum. How do you see if a number is the smallest number and then how do you see if that number is the largest number?

[Alenik1989]

Interesting way of approaching the problem. In that method you work your way down, but what about a line that had over 100 values to compare. That method would take a while to go through.

What are you really interested in? minimum and maximum. Think about that, you only want to know minimum and maximum. How do you see if a number is the smallest number and then how do you see if that number is the largest number?

i guess i have to compare that number with the rest, then if it is higher it is a maximum and if its less its a minimum.
but in this method i have to compare each # to the rest.
i cant think of any other way, can you?

[Studlyami]

you don't have to compare each number to the rest, just compare it to the minimum value and the maximum value

ex:

num1 > maxValue if yes maxValue = num1
else
num1<minValue if yes minValue = num1

num2 > maxValue if yes max Value = num2
else
num1<minValue if yes minValue = num2

now just set this up in a loop and your good to go.

[Alenik1989]

you don't have to compare each number to the rest, just compare it to the minimum value and the maximum value

ex:

num1 > maxValue if yes maxValue = num1
else
num1<minValue if yes minValue = num1

num2 > maxValue if yes max Value = num2
else
num1<minValue if yes minValue = num2

now just set this up in a loop and your good to go.

in here i just dont get what is the value of maxValue in num1>maxValue
i mean i dont know the minimum and maximum values, how can i compare the # to them?

[Studlyami]

Each one would have to have an initial value you can either set the first value to it then check each number against it. or you can set min/max to a number that would be easy to be overwritten (the 2nd way is not a good way of doing this sense you are putting constraints on the range of data).

so

max = num1;
min = num1;

now do the
num2 >max
else
num2<min

etc. You just need to set up a loop to loop through each integer value that you have.

[Alenik1989]

Each one would have to have an initial value you can either set the first value to it then check each number against it. or you can set min/max to a number that would be easy to be overwritten (the 2nd way is not a good way of doing this sense you are putting constraints on the range of data).

so

max = num1;
min = num1;

now do the
num2 >max
else
num2<min

etc. You just need to set up a loop to loop through each integer value that you have.

you see the code that i wanna use the min and max is a fstream code which is

int main ()
{
    ifstream infile;
    ofstream outfile;
    float num1,num2,num3,limit1=0,limit2=0,counter1=0,counter2=0,sum=0;
    float aver;
 
    infile.open("testin.txt");
    outfile.open("testout.txt");
 
    if (infile.fail() || outfile.fail())
    {
        cout<<"failed";
        return 1;
    }
else
    while(!infile.eof())
    {
        infile>>num1>>num2;
        limit1=num1;
        limit2=num2;
 
        while(counter1<limit1)
        {
        sum=0;
        counter2=0;
 
        while (counter2<limit2)
        {
            infile>>num3;
            outfile<<num3<<" ";
            sum+=num3;
            counter2++;
 
 
        }
        outfile<<"\nTotal      ="<<sum<<endl;
        aver=sum/limit2;
        outfile<<"Average    ="<<aver<<endl;
        outfile<<"____________________"<<endl;
        counter1++;
 
 
        }
 
    }
 
        return 0;
}

which gets an input file i format of

 2 3   2is the # of rows     and 3 is the number of #per line
and then somthing like
1 2 3
4 3 2
 

which can be with different number of rows or groups


and then the output is like

1 2 3 
Total      =6
Average    =2
____________________
4 3 2 
Total      =9
Average    =3
____________________
 

now i wanna add the min and max values below the Average for each row!!!!
i tried your suggestion but i could'nt get it right??????

[Studlyami]

okay first let me suggest that you rename some of your variables to better describe them. This would make it easier to help out. Sense you aren't storing any of the variables you are going to need a flag to tell you if you are in the beginning of a line or not. Lets use a boolean to determine this.

  //add to the top of the page with all your other variables
  int min = 0; //initialize variables 
 int max = 0; 
 bool FirstItemInLine = true; 
 
//where you reset sum and the other number 
min = 0;
max = 0
FirstItemInLine = true; // sense we just finished one line we need to assign min/max again
 
        while (counter2<limit2) //this is the loop in which you grab the line information
        {
            infile>>num3;
            outfile<<num3<<" ";
            sum+=num3;
            counter2++;
 
            if(FirstItemInLine == true)
            {
                 FirstItemInLine = false; //only do this once per line
                min = num3;
                max = num3;
            }
           else
           {
                 if(num3>max)
                       max = num3;
                 else
                      if(num3<min)
                             min = num3;
            }
        }
 

[Alenik1989]

TANXXXXXXXXXX Studlyami
that worked great
but 1 thing
why do we have to use FirstItemInLine boolean (the flag)??
it wont work without the flag?
and can u explain real quick what happened?

[Studlyami]

sure thing. The problem you were running into before is that you grab a number from the file then you compare it to max then to min, but as you stated earlier how do we know what min and max is? Also sense we needed to find the minimum and maximum value per LINE we have to know when we hit a new line so that we can assign the first value grabbed from the file to min and to max. Now we are guaranteed that min and max are values which are contained in our line. Then for the following numbers that we get from the file we compare them to min/max (which starts off as the first value in the line).

The logic looks like this
before each line reset values
grab first number in line and assign it to min and to max.
add first number to sum
grab each number following the first number and check to see if it is smaller than min or greater than max. Then add it to sum (in our case we added it to sum first)


I hope that makes sense if not let me know and ill post a clearer explanation after i get some sleep. Also, sorry for the ramble im a little sleepy :)

[Alenik1989]

Thank u very much
i got it after i review it 2 or 3 times and by reading your post!!!!!
sorry but i still dont get the flag that you have used completely!!!!!
i mean why did you use the flag here
____________________________________
//where you reset sum and the other number
min = 0;
max = 0
FirstItemInLine = true; // sense we just finished one line we need to assign min/max again //I DONT GET IT
________________________________
and then again in here
if(FirstItemInLine == true) //I THINK IVE GOT THIS PART
{
FirstItemInLine = false; //only do this once per line
min = num3; //I DONT GET THIS PART
max = num3;
}
__________________________________
at the end can you please tell me how to read a num in this case num3 twice in fstream?

[Studlyami]

Alright think back to the logic we came up with for finding minimum and maximum.
lets say our line looked like so:
100 8 150
25 75 50

our logic said to grab the first item (100) and assign it to min and max
so after the first item min = 100 and max = 100;
grab the next item (8) 8>max(which is 100) no. is 8<min(again which is 100) yes so min = 8; now max = 100, min = 8
grab the next item (150) is 150>max (still 100) yes so max = 150;
Okay our line is done. we need to grab the first item in the next line to assign the value to max and min (rather than comparing the first number to max and min). So the flag tells us that wee need to assign the value to max /min

I check the flag it is true(just started a new line)
{
set flag false
grab first item and ASSIGN it to max & min . So max = 25, min = 25.
}
I check the flag its false
{
grab next item (75) and COMPARE it to max & min. so 75> max? yes max = 75
grab next item (50) and compare it to max 50> max(75) no. 50<min(25) no.
max = 75, min = 25.

min = 0;
max = 0
FirstItemInLine = true; //start of new line so the first number in this line we need to ASSIGN the value to min and max rather than COMPARE it.
 
if(FirstItemInLine == true)// ASSIGN value grabbed from the text file(num3) and ASSIGN it to min and max 
            {
                 FirstItemInLine = false; //We just grabbed the first item in the line so    this must turn to false. 
                file>>num3;// num3 will retain this value untill we do a file>>num3 again, or until you assign a different value to it like num3=4;
 
               //lets say we grabbed a  45 from the file and that value is stored in num3.  so right now num3 = 45;
                min = num3;        //ASSIGN the first item in the line to min
                max = num3;       //ASSIGN the first item in the line to max
 
                // Right now     min = 45.  max = 45
}
else //FirstItemInLine is false
{
     //Grab next item and compare it to min and max.
     file>>num3;   //lets say we grabbed 30;
    if(num3> max)  // 30>45    NO
             max = num3;
   else
        if(num3<min)// 30<45  YES
             min = num3;
 
            // now max = 45,  min = 30
}
__________________________________
 

at the end can you please tell me how to read a num in this case num3 twice in fstream?

why do you need to
when you do a file>>num3. that value in the file is stored as the integer num3. That value wont change untill you tell the program to change it by doing another file>>num3 or a num3 = 5. I tried to address that when i broke the program down above.

[TheVith]

Just do a loop and compare one to the next and have a new variable hold the max number, its easy to do with an array.

#include <iostream>
using namespace std;
 
void main()
{
 
      int grades[10]={1,5,3,7,5,9,7,11,9,8};
      int max=0;
      for(int i=0;i<=9;i++)
      {
          if(grades[i]>max)
          {
          max=grades[i];
          }
          cout<<"At loop "<<i<<" max is "<<max<<endl;
      }
 
      cout<<endl<<"Final Max is "<<max<<endl;
 
}

[Alenik1989]

Tanx Very Much
I Got It
Iwrote The Program Perfectly!!!!