From 2aca08a7665b5650dc344bd71f9ad1bcae42f044 Mon Sep 17 00:00:00 2001
From: Marat Izmailov <marat.izmailov@student.tuke.sk>
Date: Mon, 7 Oct 2024 12:43:15 +0000
Subject: [PATCH] Update cv3/program.c

---
 cv3/program.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/cv3/program.c b/cv3/program.c
index 1c85e15..9f647d0 100644
--- a/cv3/program.c
+++ b/cv3/program.c
@@ -11,32 +11,41 @@ struct stack {
     int size;
 };
 
-
+// Function declarations
 void push_stack(struct stack* stack, float value);
 float pop_stack(struct stack* stack);
 void print_stack(struct stack* stack);
 int is_number(const char* str);
 
-
 int main() {
     struct stack mystack;
-    memset(&mystack, 0, sizeof(struct stack)); 
+    memset(&mystack, 0, sizeof(struct stack)); // Initialize the stack
 
     char input[50];
     while (1) {
         printf("Enter a number or an operator (+, -, *, /): ");
         if (!fgets(input, sizeof(input), stdin)) {
-            break; 
+            break; // Exit on EOF
         }
-        
+        // Remove trailing newline character
         input[strcspn(input, "\n")] = 0;
 
+        // Check if the input is empty
+        if (strlen(input) == 0) {
+            printf("no input\n");
+            break;
+        }
+
         if (is_number(input)) {
-            
+            // Convert input to float and push onto stack
             float value = atof(input);
             push_stack(&mystack, value);
         } else if (strlen(input) == 1 && strchr("+-*/", input[0])) {
-            
+            // Perform operation
+            if (mystack.size < 2) {
+                fprintf(stderr, "Error: Not enough values in stack.\n");
+                exit(EXIT_FAILURE);
+            }
             float b = pop_stack(&mystack);
             float a = pop_stack(&mystack);
             float result;
@@ -68,28 +77,28 @@ int main() {
             exit(EXIT_FAILURE);
         }
 
-        
+        // Print the current stack
         print_stack(&mystack);
     }
 
     return 0;
 }
 
-
+// Push a value onto the stack
 void push_stack(struct stack* stack, float value) {
-    assert(stack->size < STACK_SIZE); 
+    assert(stack->size < STACK_SIZE); // Ensure there's space in the stack
     stack->values[stack->size] = value;
     stack->size += 1;
 }
 
-
+// Pop a value from the stack
 float pop_stack(struct stack* stack) {
-    assert(stack->size > 0); 
+    assert(stack->size > 0); // Ensure there's something to pop
     stack->size -= 1;
     return stack->values[stack->size];
 }
 
-
+// Print the contents of the stack
 void print_stack(struct stack* stack) {
     for (int i = 0; i < stack->size; i++) {
         printf("%.2f ", stack->values[i]);
@@ -97,7 +106,7 @@ void print_stack(struct stack* stack) {
     printf("\n");
 }
 
-
+// Check if the input string is a valid number
 int is_number(const char* str) {
     char* endptr;
     strtod(str, &endptr);