BMI classification structure - c

Question

I am working on an assignment in C where I have to read in multiple people's heights and weights and determine their bmi. I then classify them into their respective bmi categories, but I am getting stuck on how to do this properly, this is my code thus far:
# include <stdio.h>
int main () {
int people;
double bmi, weight, inches;
printf("How many peoples? > ");
scanf("%d", &people);
do {
printf("Enter height (inches) and weight (lbs) (%d left) > ", people);
scanf("%lf %lf", &inches, &weight);
people--;
}
while (people > 0);
bmi = (weight / (inches * inches)) * 703;
if (bmi < 18.5) {
printf("Under weight: %d\n", people);
}
else if (bmi >= 18.5 && bmi < 25) {
printf("Normal weight: %d\n", people);
}
else if (bmi >= 25 && bmi < 30) {
printf("Over weight: %d\n", people);
}
else if (bmi >= 30) {
printf("Obese: %d\n", people);
}
return 0;
}
where am i going wrong? where do i fix this code?

Answer 1

Use some data structure for storing data. You are getting input for more than one people but, finally processed for one person.
And also people--; is done. so people variable is decremented up to zero, which makes while to exit without executing your BMI calculation.
Modified Code:
#include <stdio.h>
#define MAX_PEOPLE 100
int main () {
int people;
double bmi[MAX_PEOPLE], weight[MAX_PEOPLE], inches[MAX_PEOPLE];
int index = 0;
printf("How many peoples? > ");
scanf("%d", &people);
index = people;
do {
printf("Enter height (inches) and weight (lbs) (%d left) > ", index);
scanf("%lf %lf", &inches[index], &weight[index]);
index--;
}while (index > 0);
for(index = 0; index < people; index++)
{
bmi[index] = (weight[index] / (inches[index] * inches[index])) * 703;
if (bmi[index] < 18.5) {
printf("Under weight: %d\n", index);
}
else if (bmi[index] >= 18.5 && bmi[index] < 25) {
printf("Normal weight: %d\n", index);
}
else if (bmi[index] >= 25 && bmi[index] < 30) {
printf("Over weight: %d\n", index);
}
else if (bmi[index] >= 30) {
printf("Obese: %d\n", index);
}
}
return 0;
}

Answer 2

Right now you are processing the same data.
Each time you assign a new value to weight the old one is erased.
You could create multiple variables like so:
double weight1, weight2, weight3, weight4, ...etc (highly unpractical!!)
or
create an array of doubles:
double weight[100];
and refer to each specific double variable like this:
scanf("%lf %lf", inches[0], weight[0]);
scanf("%lf %lf", inches[1], weight[1]);
scanf("%lf %lf", inches[2], weight[2]);
You see where i-m getting at ? you can manipulate the array tru a for loop.