# Error: Expression must have integral or unscoped enum type

``````#include <iostream>
#include <iomanip>
#include <string>
#include <algorithm>
#include <sstream>

using namespace std;

int main(){

float size;

float sumNum = 0;
float maxNum, minNum;
float mean;
float totalDev = 0;
float devSqr = 0;
float stdDev;

//Create a user input size
std::cout << "How many number would you like to enter? ";
std::cin >> size;
float *temp = new float[size];

//Getting input from the user
for (int x = 1; x <= size; x++){
cout << "Enter temperature " << x << ": ";
cin >> temp[x];
}

//Output of the numbers inserted by the user
cout << endl << "Number --- Temperature" << endl << endl;
for (int x = 1; x <= size; x++){
cout << "   " << x << "   ---     " << temp[x] << endl;
sumNum = sumNum + temp[x];
}

//Calculating the Average
mean = sumNum / size;
maxNum = minNum = temp;

for (int x = 1; x <= size; x++){
if (maxNum < temp[x]){
maxNum = temp[x];
}
if (minNum > temp[x]){
minNum = temp[x];
}
}

//Calculating Sample Standard Deviation
for (int x = 1; x <= size; x++){
totalDev = totalDev + (temp[x] - mean);
devSqr = devSqr + (pow((temp[x] - mean), 2));
}
stdDev = sqrt((devSqr / (size - 1)));

cout << endl << "The sum: " << sumNum << endl; //the sum of all input
cout << "The mean: " << mean << endl; //calculate the average
cout << "Maximum number: " << maxNum << endl; // print biggest value
cout << "Minimum number: " << minNum << endl; // print smallest value
cout << "The range between the maximum and the minimum: " << maxNum - minNum << endl; //the range
cout << "Deviation: " << totalDev << endl;
cout << "The squares of deviation: " << devSqr << endl;
cout << "The Standard Deviation: " << setprecision(1) << fixed << stdDev << endl;

system("pause");
}
``````

I want to get the size of the array from the user, but when I’m using (`float *temp = new float[size];`), I got an error “expression must have integral or unscoped enum type.” When I input the number, it working nicely up until to the range number. After that, start from deviation to the standard deviation, the calculation all messed up.

If I use `int` for the ‘size’ and keep the ‘temp’ as `float`, it gave me different error.

How can I fix this?

## Solution

Your variable `size` is declared as: `float size;`

You can’t use a floating point variable as the size of an array – it needs to be an integer value.

You could cast it to convert to an integer:

``````float *temp = new float[(int)size];
``````

Your other problem is likely because you’re writing outside of the bounds of the array:

``````   float *temp = new float[size];

//Getting input from the user
for (int x = 1; x <= size; x++){
cout << "Enter temperature " << x << ": ";

// cin >> temp[x];
// This should be:
cin >> temp[x - 1];
}
``````

Arrays are zero based in C++, so this is going to write beyond the end and never write the first element in your original code.

Source: StackOverflow.com