Time/pitchshift in c - c

Question

I'm fairly new to C. As part of a Uni project, I'm required to put together a programme that processes audio in some form. So, I've decided to make a pitch shifter. So far, I've managed to at least make the program process the audiofile, if not actually alter the sound. I've looked into using samplerate, but from what I've gathered, it won't give me the desired outcome.
I've downloaded and compiled the rubberband library but I'm not really sure where to start using it in conjunction with my work. I was just wondering if anyone has any tips/experience with it, perhaps to achieve similar things?
void shiftsoundfile() {
//Part 1 - File input and reading
SNDFILE *inputsf, *outputsf;
SF_INFO ininfo, outinfo2;
SRC_DATA src_data;
static float datain [BUFFER_LEN];
static float dataout [BUFFER_LEN];
int readfile;
const char *inputsfname = "Scifi.wav";
const char *outputsfname = "Scifi2.wav";
ininfo.format = 0;
if ( !(inputsf = sf_open(inputsfname, SFM_READ, &ininfo)))
if (inputsf != inputsfname)
{
printf("The file could not be opened.\n");
exit(0);
}
outputsf = sf_open (outputsfname, SFM_WRITE, &ininfo);
inputsf = sf_open (inputsfname, SFM_READ, &outinfo2);
//Part 2 - Audio file conversion
//>>SOMETHING NEEDS TO GO HERE TO PERFORM THE CONVERSION<<
//librubberband perhaps, or something along these lines?...
/*float shift [BUFFER_LEN];
int j;
for (j = 0; j < readfile; j++) {
shift [j] = datain [j]; }
for (j = 0; j < readfile; j++) {
datain [j] = shift [j]; }*/ //?
//Part 3 - Outputting the new audio file
while (readfile = sf_read_float (inputsf, datain, BUFFER_LEN))
{
sf_write_float (outputsf, datain, BUFFER_LEN);
//Write's the data in the array, pointed to by outputsf, to the file
}
sf_close (inputsf); //closes the 'osf' function
sf_close (outputsf); //closes the 'csf' function