CS31 Lab 4: C Pointers

Implement your solution in stats.c, which includes some starting point code.

Your code should be modular (use at least 4 function worthy functions).

Your code should be robust (e.g., check for and handle error return values from C functions.

Your code should be written using good C style, including using meaningful variable and function names. This includes having a top-level comment describing your program, and every function should include a brief description of its behavior. Look at the C code style guide for examples of complete comments, tips on how not to wrap lines, good indenting styles and suggestions for meaningful variable and function names in your program. You may not use any global variables for this assignment.

All local variables should be declared at the beginning of the function, and then used in statements that follow. Also use meaningful names for local variables.

It should be evident that you applied top-down design when constructing your submission (e.g., there are multiple functions, each with a specific, documented role). You should have at least 4 function-worthy functions.

Remove the "TODO" comment (if you want to, you can keep the comment itself without the TODO in front if it helps you explain/layout your code.)

The get_values function: takes the name of a file containing input values, reads in values from the file into a dynamically allocated array, and returns the dynamically allocated array to the caller. The array’s size and capacity are "returned" to the caller through pass-by-pointer parameters:

float *get_values(int *size, int *capacity, char *filename);

The array of values must be dynamically allocated on the heap by calling malloc. You must start out allocating an array of 20 float values. As you read in values into the current array, if you run out of capacity:

When all of the data values have been read in from the file, the function should return the filled, dynamically allocated, array to the caller (the function’s return type is (float *). The array’s size and total capacity are "returned" to the caller through the pass-by-pointer parameters size and capacity.

After reading in the values from the file, your program should sort the array (and note that your program should be able to easily compute min, max and median on a sorted array of values). See the Tips section about how to re-use your sort function from the Lab 2.

When run, your program’s output should look like the output shown below from a run of a working program. To make grading easier, your output must match the example as closely as possible.

You should not assume that we will test your code with the sample input files that have been provided.

For full credit, your program must be free of valgrind errors. Do not forget to close the file you opened! If you don’t, valgrind will likely report a memory leak.

$ ./stats large.txt
Results:
num values:         62
       min:     -1.801
       max:      3.317
      mean:      0.794
    median:      1.121
   std dev:      1.158
unused array capacity: 18

Then, go back and add in code for larger input files, requiring: (a) malloc-ing more space, (b) copying old values to the new larger space and (c) freeing up the old space (this step is really important!)