Question

I’m writing a statistical calculator, with 3 different calculation options. The problem is whenever I choose the 2nd option, it wants to print both the answer from the 1st option and the 2nd option. When I choose the 3 option, it just prints the answer the the 3rd option(the wrong answer, but thats probably a mishap in the formula). Here is the results:

Please Enter a number of inputs
3
Please enter number 1
1
Please enter number 2
2
Please enter number 3
3
Statistical Calculator Menu
(1) Mean
(2) Standard Deviation
(3) Range
(4) Restart/Exit
2
Here is the Mean 2.0Standard Devition is 0.8

Now I thought it might be an issue with how I’m calling each function, but the best I can tell thats not the case. Then I thought it might be a value that I didn’t initialize, but it seems as though thats not it either. I just need another pair of eyes to see where I went wrong here.

#include <stdio.h>
#include <conio.h>
#include <math.h>

const int MAX_DATA=8;
void menu(float numbers[], int amount);
float mean(float numbers[],int amount);
float standard_dev(float numbers[], int amount);
float range( float numbers[], int amount);

int main()
{
    int i=0, amount=0;
    float numbers[MAX_DATA];
    printf("Please Enter a number of inputs \n");
    scanf("%d", &amount);
    if (amount>MAX_DATA)
    {
        printf("You entered too many numbers");
    }
    else
    {
        for (i=0; i<amount; i++)
        {
            printf("Please enter number %d\n", i+1);
            scanf("%f",&numbers[i]);
        }
        menu(numbers,amount);
    }
    getch();
    return 0;
}
void menu(float numbers[],int amount)
{
    int input2=0;
    printf("Statistical Calculator Menu");
    printf("\n(1) Mean\n(2) Standard Deviation\n(3) Range\n(4) Restart/Exit\n");
    scanf("%d",&input2);
    if(input2==1)
    {
        mean(numbers,amount);
    }
    if  (input2==2)
    {
        standard_dev(numbers,amount);
    }
    if (input2==3)
    {
        range(numbers,amount);
    }
}
float mean(float numbers[],int amount)
{
    int i;
    float sum=0;
    float average=0;
    for (i=0; i<amount; i++)
    {
        sum=sum+numbers[i];
    }
    average=sum/amount;
    printf("Here is the Mean %.1f", average);
    return average;
}
float standard_dev(float numbers[], int amount)
{
    float sdev=0,dev=0,sumsqr=0,variance=0;
    int i;
    float mean2=0;
    mean2=mean(numbers,amount);
    for (i=0; i<amount; i++)
    {
        dev=numbers[i]-mean2;
        sumsqr+=dev*dev;
    }
    variance=sumsqr/(float)amount;
    sdev=sqrt(variance);
    printf("Standard Devition is %.1f", sdev);
    return sdev;
}
float range(float numbers[],int amount)
{
    int i;
    float diff=0;
    for (i=0; i<=amount; i++)
    {
        diff=numbers[amount]-numbers[1];
    }
    printf("%f\n",diff);
    return diff;
}

Answer 1

float standard_dev(float numbers[], int amount)
{
 float sdev=0,dev=0,sumsqr=0,variance=0;
 int i;
 float mean2=0;
 mean2=mean(numbers,amount); // Here it is.

It calls the mean function, which actually prints something 🙂 You can add boolean flag shouldPrint to functions and pass it as true when you want to print it.

Also, this problem is easily solvable with simple debugging your code…if actually looking at it doesn’t seem to help…