Why all these errors when building this C project? - c

Question

I'm coding some similar programs in C as part of an XCode project. As this new program needs to exhibit some slightly different functionality to what the 1st working iteration was, I thought targets were the best thing to use.
So I tried to create a new target, and did it the way I thought was the right way from googling how to (in XCode). But on compilation, I get way too many errors.
Here is a screen of the errors I get:
I see that it's having a problem with loads of different characters, so I'm sure it's probably a simple problem like some missing files. But I didn't know what to Google so I hope it's okay that I'm asking.
On a related note, does anyone know why my first version of the program, called main.c, didn't need to include a header file like the one above did?
Thanks!
EDIT:
Here's the code from the new target, which is practically identical to the so far unchanged first version of the program:
/*
* ScalarProduct.c
* Concurrency_Practical1
*
* Created by Chucky on 11/03/2012.
* Copyright 2012 __MyCompanyName__. All rights reserved.
*
*/
#include "ScalarProduct.h"
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
//the final answer
int finalScalarProd;
//random variable
int rand_seed=10;
int rand()
{
int n;
n = random()%11;
//printf("%d\n", n);
return(n);
}
void* getScalarProduct(void *arg)
{
//index for loop
int i;
//scalarProduct of 10 integers
int * scalarProd = (int *) arg;
//my two arrays
int list1[10];
int list2[10];
for (i=0; i<10; i++) {
list1[i] = rand();
list2[i] = rand();
*scalarProd += list1[i]*list2[i];
printf("%d:\t\t %d\t\t %d\t\t %d\t\t\n", i, list1[i], list2[i], list1[i]*list2[i]);
}
return((void*)scalarProd);
}
int main (int argc, const char * argv[]) {
// insert code here...
pthread_t t1, t2;
int sp1= 0, sp2 = 0;
printf("Index\t List1\t List2\t Product\n\n");
pthread_create( &t1, NULL, getScalarProduct, &sp1);
pthread_create( &t2, NULL, getScalarProduct, &sp2);
pthread_join( t1, NULL);
pthread_join( t2, NULL);
printf("\nScalar Products: %d %d\n", sp1, sp2);
finalScalarProd = sp1 + sp2;
printf("Result: %d\n", finalScalarProd);
return 0;
}

Answer 1

From the errors, it almost looks as if you are mixing Objective-C headers and compiling with the C compiler. It's still hard to tell though.

Answer 2

Your project is including/importing the AppKit-Header, which is ObjectiveC and not pure C.
As your quoted source does not mention it, I would bet that it is imported within the precompiled header. Check your project's precompiled header for such entry/ies. It will be named just like your project, with the extension .pch. You may want to remove any ObjectiveC imports.
Also check if you used any ObjectiveC frameworks in your project. When in doubt, remove all listed frameworks from your project.