homework.c

/*******************************************
Processo e Desenvolvimento de Software
Aluno: rodrigo caldas de moura duarte

gcc test1.c -o test1 -lm;./test1
*******************************************/

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

/* retorna desvio padrao */

double stdev(int buff[], int bfsize)
{
	int cnt = 0;
	double aqr = 0, mean = 0, dif = 0;
    
 	for(cnt=0;cnt != bfsize;cnt++)
	mean += buff[cnt];
	
	mean = mean / cnt;
    
	for(cnt=0;cnt != bfsize;cnt++)
	{
            dif = buff[cnt] - mean;
	    aqr += (dif * dif);
        }

	aqr = (double) aqr / (bfsize - 1);

	return sqrt(aqr);
}

/* exemplo de uso */

int main()
{
	int *buff, bfsize = 0, cnt = 0;

	fprintf(stdout,"\nDe quantos elementos deseja tirar a media e o desvio? ");
	scanf("%i",&bfsize);

	buff = (int *) calloc(bfsize, sizeof(int));

	if(!buff || bfsize == 0)
	{
		fprintf(stderr,"erro de memoria ou entrada nula\n");
		return -1;
	}

	for(cnt = 0; cnt != bfsize; cnt++)
	{
		printf(" \nEntre com a [%i] entrada.. : ",cnt + 1);
		scanf("%i",buff+cnt);
	}

	fprintf(stdout," Standard Variation: %f \n",stdev(buff,bfsize));

       //system("pause"); //aff windows babaca
	
        free(buff);
	return 0;
}