Get wrong calculation for mean and standard deviation - c

Question

I'm trying to calculate the mean and standard deviation using following
code segment. I am not getting any compile errors.
When I run it using .txt file, the output
appears following way:
"
"is not a valid integer
with wrong summation, mean and standard deviation and also Can't input double values.
int main ( int argc, char *argv[] )
{
if(buffer == NULL)
{
}
double result = fread(buffer,1,lSize,file);
if(result != lSize){
}
else{
char *str = strtok(buffer," ,");
int count = 0;
while(str != NULL){
double val = (int) strtol(str,&str,10);
if(*str != ' ' && *str != '\0')
{
}
else{
if(count == 0)
{
root = malloc(sizeof(struct node));
root->next = NULL;
root->value = val;
current = root;
count++;
}
else{
double x = createNode(current,val);
}
}
str = strtok(NULL," ,");
}
}
current = root;
printf("Sum is %lf and link count is %lf\n",
getSummation(current), getNodeCount(current));
double mean = getMean(getSummation(current),getNodeCount(current));
double stdev = getStandardDeviation(root, mean,getNodeCount(current));
fclose( file );
free(buffer);
}
}
return 0;
}
int createNode(struct node *n,double val)
{
if(n != NULL){
while(n->next != NULL)
{
n = n->next;
}
n->next = malloc(sizeof(struct node));
n = n -> next;
n -> value = val;
n -> next = NULL;
}
return 1;
}
int getSummation(struct node *element){
double sum = 0.0f;
if(element != NULL)
{
while(element != NULL)
{
sum = sum + element->value;
element= element->next;
}
}
else
{
printf("Null Point Exception thrown");
}
return sum;
}
int getNodeCount(struct node *link)
{
int count = 0;
while(link != NULL)
{
}
return count;
}
double getMean(double summation,int numberOfNodes)
{
}
double getStandardDeviation(struct node *link, double mean,int linkCount)
{
while(link != NULL)
{
}
stdev = sqrt((diffrenceSummation)/(linkCount - 1));
return stdev;
}

Answer 1

1) Add prototypes before main()
//double getSummation(struct node*element);
int getSummation(struct node *element);
int createNode(struct node *n,double val);
int getNodeCount(struct node *link);
#include <math.h>
2) Use consistent format specifiers
//printf("Summation is %lf and link count is %lf\n",
// getSummation(current), getNodeCount(current));
printf("Summation is %d and link count is %d\n",
getSummation(current), getNodeCount(current));
3) Various castings are questionable
// mean = (double)summation/(double)numberOfNodes;
mean = summation/numberOfNodes;
// double linkValue = (double) link->value;
double linkValue = link->value;
// buffer = (char*) malloc(sizeof(char)*lSize);
buffer = malloc(lSize);
// double val = (int) strtol(str,&str,10);
double val = strtol(str,&str,10);