feat: add prime

prime/go.c

@@ -0,0 +1,24 @@
+/* go.c
+   Takes one input argument from the command line, an integer,
+   and returns 1 if the number is prime, and 0 if it is not.
+
+   Compile with: gcc -o go go.c primes.c 
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "primes.h"
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    printf("error: must provide a single integer value to test\n");
+    return 1;
+  }
+  else {
+    int n = atoi(argv[1]);
+    int prime = isPrime(n);
+    printf("isPrime(%d) = %d\n", n, prime);
+    return 0;
+  }
+}
+

prime/makefile

@@ -0,0 +1,14 @@
+RM = /bin/rm -f
+CC = gcc
+CFLAGS = -Wall
+DEPS = primes.h
+OBJ = go.o primes.o
+#%.o recipe with dependencies
+%.o: %.c $(DEPS)
+	$(CC) $(CFLAGS) -c -o $@ $<
+#go recipe with dependencies
+go: $(OBJ)
+	gcc $(CFLAGS) -o $@ $^
+#
+clean:
+	$(RM) $(OBJ) go *~

prime/makefile1

@@ -0,0 +1,4 @@
+# go: recipe with dependencies
+go: go.c primes.c
+	gcc -o go go.c primes.c
+

prime/primes.c

@@ -0,0 +1,16 @@
+int isPrime(int n) {
+
+  // returns 0 if not prime, 1 if prime
+  
+  if (n<2) return 0;         // first prime number is 2
+  if (n==2) return 1;        // ensure 2 is identified as a prime
+  if ((n % 2)==0) return 0;  // all even numbers above 2 are not prime
+  
+  int i;
+  for (i=3; i*i < n; i++) {  // test divisibility up to sqrt(n)
+    if ((n % i) == 0) {
+      return 0;
+    }
+  }
+  return 1;
+}

prime/primes.h

@@ -0,0 +1,7 @@
+/*We can use CPP tricks to avoid parsing the same header file more than once*/
+#ifndef PQ_CON_INFO_H
+# define PQ_CON_INFO_H
+
+int isPrime(int n); // returns 0 if n is not prime, 1 if n is prime
+
+#endif /* PQ_CON_INFO_H */

prime/readme.md

@@ -0,0 +1 @@
+[source](https://gribblelab.org/teaching/CBootCamp/12_Compiling_linking_Makefile_header_files.html)

sprintf/main.c

@@ -13,6 +13,7 @@ int main()
   char * secret = "secret";
   char * host = "localhost";
   char * db = "vbn_data";
+  /*TODO How is const defined?*/
   const int pqConInfoSize = 100;
   char pqConInfo[pqConInfoSize];