Fix errors from reordering problem numbers, and add P2 solution

include/p1.h

@@ -1,5 +1,5 @@
-#ifndef P2_H
-#define P2_H
+#ifndef P1_H
+#define P1_H
 
 void find_avg_min_max(double* arr, int size,
 		      double* out_avg, double* out_min, double* out_max);

include/p2.h

@@ -0,0 +1,7 @@
+#ifndef P2_H
+#define P2_H
+
+int pop_front(int* arr, int size);
+
+#endif
+

include/p5.h

@@ -1,5 +1,5 @@
-#ifndef P1_H
-#define P1_H
+#ifndef P5_H
+#define P5_H
 
 int count_alphanumeric(const char* str);
 

src/main.c

@@ -3,14 +3,20 @@
 #include "p1.h"
 #include "p2.h"
 #include "p3.h"
+#include "p5.h"
+
+void print_int_arr(int* arr, int size) {
+	for (int i = 0; i < size; ++i) {
+		printf(" %d", arr[i]);
+	}
+
+	putchar('\n');
+}
 
 int main(void) {
 	// Problem 1
-	int num_alphanum = count_alphanumeric("Hello World!!");
-	printf("Number of alphanumeric characters in \"Hello World!!\": %d\n", num_alphanum);
-
-	// Problem 2
-	double arr[8] = {
+	printf("Problem 1:\n");
+	double p1_arr[8] = {
 		2.5, 4.3, 8.1, -7.4, 2.0, 1.0, 3.0, 4.0
 	};
 
@@ -18,14 +24,31 @@ int main(void) {
 	double min = 0;
 	double max = 0;
 
-	find_avg_min_max(arr, 8, &avg, &min, &max);
+	find_avg_min_max(p1_arr, 8, &avg, &min, &max);
 
 	printf("Average: %.2lf, Min: %.2lf, Max: %.2lf\n", avg, min, max);
 
+	// Problem 2
+	printf("Problem 2:\n");
+	int p2_arr[16] = { 1, 2, 3, 4, 5 };
+	int size = 5;
+
+	print_int_arr(p2_arr, size);
+
+	size = pop_front(p2_arr, size);
+
+	print_int_arr(p2_arr, size);
+
 	// Problem 3
+	printf("Problem 3:\n");
 	double sum_of_file = sum_file("input_p3.dat");
 
 	printf("Sum of file: %.2lf\n", sum_of_file);
+	//
+	// Problem 5
+	printf("Problem 5:\n");
+	int num_alphanum = count_alphanumeric("Hello World!!");
+	printf("Number of alphanumeric characters in \"Hello World!!\": %d\n", num_alphanum);
 
 	return 0;
 }

src/p2.c

@@ -0,0 +1,12 @@
+#include "p2.h"
+
+int pop_front(int* arr, int size) {
+	int new_size = size - 1;
+
+	for (int i = 0; i < new_size; ++i) {
+		arr[i] = arr[i + 1];
+	}
+
+	return new_size;
+}
+