Reading floats into an array

Question

How could I read let\'s say 10 floats and store them in an array without wasting any memory?

Answer 1

Aha. It's not reading the floats that's the problem, it's the memory. You read in i, and you need an array that holds exactly i floats.

This really does smell like homework, which is fine, but I'm too much the teacher to give you the full answer. So I'll tell you, what you need is a C function named malloc() and a C operator (it looks like a function but it's actually built into the language) named sizeof.

Have a look at this tutorial.

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Yup, you got it there. Here's the code from your comment, formatted.

int n,index;
float temp;
scanf("%d",&n);
float *pValues=(float *)calloc(n,sizeof(float));
for(index=0;index

I'd do it with two changes:

1. Its more idiomatic to use malloc for anything besides characters
2. In C, arrays and pointers have a very close relationship; in fact *(pValues+index) is exactly equivalent to pValues[index].

So I'd rewrite this as:

int n,index;
float temp;
scanf("%d",&n);
float *pValues=(float *)malloc(n*sizeof(float));
for(index=0;index

Let's look at one more transformation of the code. You have pValues, which is a pointer to float. You have &temp, which is also a pointer to float, because & is the address-of operator and temp is a float. AND, you're just doing pointer arithmetic with your index. So, we could rewrite this one more time as:

int n,index;    // Don't need temp
scanf("%d",&n);
float *pValues=(float *)malloc(n*sizeof(float));
for(index=0;index

Now, quiz question: what would happen if you made the loop

for(index=0;index