Initial commit - move project to github

.gitignore

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+# Prerequisites
+*.d
+
+# Object files
+*.o
+*.ko
+*.obj
+*.elf
+
+# Linker output
+*.ilk
+*.map
+*.exp
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Libraries
+*.lib
+*.a
+*.la
+*.lo
+
+# Shared objects (inc. Windows DLLs)
+*.dll
+*.so
+*.so.*
+*.dylib
+
+# Executables
+*.exe
+*.out
+*.app
+*.i*86
+*.x86_64
+*.hex
+
+# Debug files
+*.dSYM/
+*.su
+*.idb
+*.pdb
+
+# Kernel Module Compile Results
+*.mod*
+*.cmd
+.tmp_versions/
+modules.order
+Module.symvers
+Mkfile.old
+dkms.conf

main.c

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+#include <stdio.h>
+#include "stack.h"
+
+
+/* - Program Start - */
+
+int main(int argc, char *argv[]) {
+    printf("Making stack: ");
+    Node *stack = make_stack();
+    if (!stack) {
+        printf("fail\nProgram terminated.\n");
+        return 0;
+    }
+    printf("success\n\n");
+
+    printf("Peaking at empty stack behaves as expected:   %s\n", peak(stack) == '\0' ? "success" : "fail");
+    printf("Popping from empty stack behaves as expected: %s\n", pop(stack) == '\0' ? "success" : "fail");
+
+    printf("\nPushing alphabet to stack...\n");
+    for (char c = 'a'; c <= 'z'; c++) {
+	    printf("Pushing %c to stack: %s\n", c, push(stack,c) ? "success" : "fail");
+    }
+
+    printf("\nTesting peak and pop...\n");
+    printf("peak: '%c'\n", peak(stack));
+    printf("pop:  '%c'\n", pop(stack));
+    printf("pop:  '%c'\n\n", pop(stack));
+
+    printf("Destroying stack:              %s\n", free_stack(stack) ? "success" : "fail");
+    printf("Setting stack pointer to NULL: %s\n\n", (stack = NULL) ? "fail" : "success");
+
+    printf("Pushing to NULL stack behaves as expected:   %s\n", push(stack, 'a') ? "fail" : "success");
+    printf("Peaking at NULL stack behaves as expected:   %s\n", peak(stack) == '\0' ? "success" : "fail");
+    printf("Popping from NULL stack behaves as expected: %s\n", pop(stack) == '\0' ? "success" : "fail");
+
+    return 0;
+}

stack.c

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+#include <stdbool.h>
+#include <stdlib.h>
+#include "stack.h"
+
+
+/* - STRUCTS - */
+
+
+// Nodes contain stored data and a pointer to the next node.
+struct node {
+	char character;
+	struct node *next;
+};
+
+
+/* - FUNCTIONS - */
+
+
+// Creates a blank node that acts as the accessor for the stack structure. The
+// returned pointer will be NULL if malloc fails to allocate this node.
+Node *make_stack() {
+	Node *new_stack = (Node *)malloc(sizeof(Node));
+	if (new_stack) {
+		new_stack->character = '\0';
+		new_stack->next = NULL;
+	}
+	return new_stack;
+}
+
+
+// Adds a node to the top of the stack containing the value c. Returns false if
+// the stack is NULL.
+bool push(Node *stack, char c) {
+    if (!stack) return false;
+    Node *node = (Node *)malloc(sizeof(Node));
+	if (!node) return false;
+    node->next = stack->next;
+    node->character = c;
+    stack->next = node;
+	return true;
+}
+
+
+// Removes node at top of stack and returns its stored value
+char pop(Node *stack) {
+	if (stack && stack->next) {
+		Node *temp = stack->next;
+        stack->next = temp->next;
+        char return_value = temp->character;
+		free(temp);
+		return return_value;
+	}
+	return '\0';
+}
+
+
+// Returns the value at the top of the stack without removing the node.
+char peak(Node *stack) {
+	if (stack && stack->next) {
+		return stack->next->character;
+	}
+	return '\0';
+}
+
+
+// Frees every node in the stack structure. Returns false if the stack is NULL.
+bool free_stack(Node *stack) {
+    if (!stack) return false;
+	Node *temp = stack;
+	while (stack) {
+		temp = stack->next;
+		free(stack);
+		stack = temp;
+		// printf("free node\n");
+	}
+    return true;
+}

stack.h

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+#ifndef STACK_H
+#define STACK_H
+
+#include <stdbool.h>
+
+typedef struct node Node;
+Node *make_stack(void);
+bool push(Node *, char);
+char pop(Node *);
+char peak(Node *);
+bool free_stack(Node *stack);
+
+#endif
+