C++ Calculator App, can't get MIN & MAX to work.

[sprockets]

I'm trying to create a calculator, but for my mix and max, I'm not getting the correct results. I'm pretty sure this is bad but how to fix it?

for (i = 1; i <= n; i = i + 1) {
    printf("Enter data item %d: ", i);
    scanf("%f", &data);
 
    sumx = sumx + data;
    sumx2 = sumx2 + (data*data);
 
}
 
 
mean = sumx / n;
var = 1.0/(n-1) * (sumx2 - (1.0/n)*sumx*sumx);
sd = sqrt(var);
 
min = 0;
max = 0;
 
    if (data > max){
      max = data;
    }
    else if(data < min)
      min = data;
    /* print the computed values */
 
 
 
    printf("\n");
    printf("     mean = %f\n", mean);
    printf(" variance = %f\n", var);
    printf("std. dev. = %f\n\n", sd);
    printf("The minimum number in the list is %d.\n", min);
    printf("THe maximum number in the list is %d.\n", max);
 
 
    return 0;
}
 

[divideby0]

I tend to skip the else

if(data >= max)
   max = data;
if(data <= min)
   min = data;
 

[sprockets]

Tried that and doesn't work. I updated the post with more code

[divideby0]

what data types are you using on your variables posted?

your parens may be important. 3 / 4 * 4 / 10 may yield goofy results if you really mean (3 / 4) * (4 / 10)
look out for any integer division

[sprockets]

Sorry not exactly sure what you mean. Everything in the code works except for the 'min' and 'max' thing. It's just printing out the last number the user enters.

min and max are both set as integers if that's what you're asking.

[divideby0]

It's just printing out the last number the user enters

I didn't catch that in the code you posted - sorry. You'll want to check data for max or min within the loop.

for(i=0; i < n; ++i)
{
   // prompt the user for input
   // store user input in data
   // check data for either max and min
   // manipulate sumx and sumx2
}
 
// other stuff
 

[sprockets]

Here's my for loop, but still the same problem. I deleted what I had before

 for (i = 1; i <= n; i++) {
    printf("Enter data item %d: ", i);
    scanf("%f", &data);
    if (data > max){
      max = data;
    }
    if(data < min) {
      min = data;
    }
    sumx += data;
    sumx2 += (data*data);
 
  }

[weaknessforcats]

What are the data types of min, max, data, sumx, var, sd, etc...

They better all be floating point or all be integers. You cannot mix integer and floating point arithmetic.

[sprockets]

I originally had min and max as integers, but changed them to floats and altered the code. Still same results however

[weaknessforcats]

It appears that min and max are set outsde the loop so you are using the last value of data. Maybe the min/max should be placed inside the loop where it will be exposed to each data value entered.

Please use integers. Floating point comparisons are harder to work with.

[sprockets]

I did change my code to put it in the for loop, but still same problem

[weaknessforcats]

So what does your code look like now?

[sprockets]

#include <stdio.h>

#include <math.h>
 
int main() {
    int i;              /* loop variable             */
    int n;              /* number of data items      */
    float mymin;            /*Minumum value              */
    float mymax;            /*Maximum value              */
    float data;         /* data item                 */
    float sumx;         /* sum of data items         */
    float sumx2;        /* sum of squared data items */
    float mean;         /* mean of the data          */
    float var;          /* variance of the data      */
    float sd;           /* std. deviation of data    */
 
    /* Get the number of data items from the user */
 
    printf("How many numbers do you need to enter (n)? ");
    scanf("%d", &n);
 
    while(n < 0) {
      printf("You must enter a positive number. \n");
      scanf("%d", &n);
    }
 
 sumx = sumx2 = 0.0;
 
 
 
    for (i = 1; i <= n; i = i + 1) {
      printf("Enter data item %d: ", i);
      scanf("%f", &data);
      if(data > mymax){
        mymax = data;
      }
      if(data < mymin){
        mymin = data;
      }
      sumx = sumx + data;
      sumx2 = sumx2 + (data*data);
 
    }
 
 
 
    mean = sumx / n;
    var = 1.0/(n-1) * (sumx2 - (1.0/n)*sumx*sumx);
    sd = sqrt(var);
 
 
 
    printf("\n");
    printf("mean = %f\n", mean);
    printf("variance = %f\n", var);
    printf("std. dev. = %f\n\n", sd);
    printf("Minimum value is %f\n", mymin);
    printf("Maximum value is %f/n", mymax);
 
    return 0;
}
 

Sorry about indentation problems.

[donbock]

Where are mymax and mymin defined? What are their initial values?

[sprockets]

Sorry about that, I kinda copied and pasted some and freehanded the rest. Float min = mymin and max = mymax

[weaknessforcats]

Oops:

printf("How many numbers do you need to enter (n)? ");
    scanf("%d", &n);
 
    while(n < 0) {
      printf("You must enter a positive number. \n");
      scanf("%d", &n);
     }
 

The two scanf calls put data into the same variable.

[sprockets]

Ohhh haha I see that now. THanks, I fixed it. Works great now