# C program to calculate standard deviation

In this tutorial, we are going to write a C Program to calculate standard deviation in C Programming with practical program code and step-by-step full complete explanation.

## C Program to calculate the standard deviation.

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

#define MAXSIZE 100

void main()
{
int i,n;
float value[MAXSIZE], deviation;

int sum,sumsqr,n=0;

float mean, variance, stddeviation;

printf("Input values: input -1 to end\n");

for(i=1;i<MAXSIZE;i++)
{
scanf("%f",&value[i]);

if(value[i]== -1)
break;
sum += value[i];
n+=1;
}

mean=sum/(float)n;

for(i=1;i<=n;i++)
{
deviation = value[i]-mean;
sumsqr += deviation*deviation;
}

variance = sumsqr/(float)n;
stddeviation=sqrt(variance);

printf("\nNumber of items: %d",n);
printf("\nMean: %f",mean);
printf("\nStandard deviation: %f",stddeviation);
}
```

### Output

```
Input values: input -1 to end
65 9 27 78 12 20 33 49 -1

Number of items: 8
Mean: 36.625000
Standard deviation: 23.510303
```