Importing functions from other c file without a header - c

Question

My assignment is to create a program that essentially tests the library I created in another c file. My issue is how I go about calling the library without the header. The library program is:
/*
Program: statlib.c
A Statistical library consisting of the following
seven functions: mean, variance, standard deviation,
sort, minimum value median, and max value.
*/
#include <math.h>
/* Calculates the mean value of the data in the list */
double mean(int totnum, double data[]) {
double meanval, sum;
int i;
sum = 0.0;
for(i=0; i<totnum; i++) {
sum += data[i];
}
meanval = sum/totnum;
return meanval;
}
// Calculate the variance of the data in the list
double variance(int totnum, double data[]) {
double meanval, sum, var;
int i;
meanval = mean(totnum, data);
sum = 0.0;
for(i=0; i<totnum; i++){
sum += (data[i] - meanval)*(data[i] - meanval);
}
var = sum/(totnum-1);
return var;
}
/* Calculate the standard deviation of data in the list */
double stdDeviation(int totnum, double data[]) {
double var, std;
var = variance(totnum, data);
std = sqrt(var);
return std;
}
/* Sorts the array data in ascending order. */
void sort(int totnum, double data[]) {
int i, j;
double temp;
/* find the smallest value in the reaming part of the array
in each iteratio staring with data[i]. */
for(i = 0; i < totnum-1; i++) {
/* compare with data[i] with data[j], swap their values */
for(j = i+1; j < totnum; j++) {
/* when data[i] > data[j], swap their values */
if(data[i] > data[j]) {
temp = data[i];
data[i] = temp;
}
}
}
}
/* Calculates the min value of an array. */
double minValue(int totnum, double data[]) {
double minval;
int i;
/* start at the intial value */
minval = data[0];
for(i = 1; i < totnum; i++) {
if(data[i] < minval) {
minval = data[i];
}
return minval;
}
}
/* Calculate the median of an array. Must be sorted first using the sort
function.*/
double median(int totnum, double data[]) {
double medianval;
if(totnum % 2) {
medianval = data[totnum/2];
}
else {
medianval = (data[totnum/2 -1] + data[totnum/2]/2.0);
}
return medianval;
}
/* Returns the maximum value of an array. */
double maxValue(int totnum, double data[]) {
double maxval;
int i;
maxval = data[0];
for(i = 1; i < totnum; i++) {
if(data[i] > maxval) {
maxval = data[i];
}
}
return maxval;
}
The program that I'm using to test the first program is:
/*
Program: teststatlib.c
This program tests my statlib.c program in order to
verify whether or not it is in working order.
*/
#include <stdio.h>
/* add code from statlib.c */
#pragma importf <statlib.c>
/* Declare extern functions so that the can be used */
extern double mean(int totnum, double data[]);
//extern double variance(int totnum, double data[]);
//extern double stdDeviation(int totnum, double data[]);
//extern void sort(int totnum, double data[]);
//extern double minValue(int totnum, double data[]);
//extern double median(int totnum, double data[]);
//extern double maxValue(int totnum, double data[]);
int main() {
int input[] = {30,90,100,84,72,40,34,91,80,62};
int totnum = sizeof(input)/sizeof(double);
printf("The unsorted array is %d.", input);
printf("The mean is ");
mean(totnum, input);
}

Answer 1

I find your question confusing because you didn't state your problem very well. In fact you never asked a question. Maybe I can still be a little helpful.
A few things that you can fix:
sizeof(input) not sizeof(input[])
the second to last print line does not do what you want. If you remove the [] then it will compile and print the address of the array (which is not what I think you want). You probably want to print each element of the array and you should consider doing it in a for loop. What you have looks very python-esk, but is not how we do things in c.
in your last line, you call mean() as if you expect it print something. I think you want to combine the last two lines to printf("The mean is %f\n", mean(totnum,input));
input needs to be declared as an array of type double. (also, you'll need to change sizeof(int) to sizeof(double) in the line below that)
I managed to compile and run your program in linux with the command gcc teststatlib.c statlib.c. I don't recognize #pragma importf <statlib.c> and that makes me suspect you might be using a development environment that I'm not familiar with.