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sk2/Makefile

@@ -0,0 +1,18 @@
+CC = gcc
+CFLAGS = -Wall
+LDFLAGS = -lm
+
+all: calculator
+
+calculator: main.o calculator.o
+	$(CC) main.o calculator.o -o calculator $(LDFLAGS)
+
+main.o: main.c calculator.h
+	$(CC) $(CFLAGS) -c main.c
+
+calculator.o: calculator.c calculator.h
+	$(CC) $(CFLAGS) -c calculator.c
+
+clean:
+	rm -f *.o calculator
+

sk2/calculator.c

@@ -0,0 +1,131 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include "calculator.h"
+
+int precedence(char c){
+    if (c == 's' || c == 'c' || c == 'l' || c == '^') return 3;
+    if (c == '*' || c == '/') return 2;
+    if (c == '+' || c == '-') return 1;
+    return 0;
+}
+
+int is_operator(char c){
+    if (c == '+' || c == '-' || c == '*' || c == '/' || c == '^')
+        return 1;
+    return 0;
+}
+
+void infix_to_postfix(const char *infix, char *postfix){
+    char stack[MAX];
+    int top = -1;
+    int i = 0, k = 0;
+
+    while (infix[i] != '\0') {
+
+        if ((infix[i] >= '0' && infix[i] <= '9') || infix[i] == '.'){
+            postfix[k++] = infix[i++];
+        }
+        else if (infix[i] == ' '){
+            postfix[k++] = ' ';
+            i++;
+        }
+        else if (strncmp(&infix[i], "sin", 3) == 0){
+            stack[++top] = 's';
+            i += 3;
+        }
+        else if (strncmp(&infix[i], "cos", 3) == 0){
+            stack[++top] = 'c';
+            i += 3;
+        }
+        else if (strncmp(&infix[i], "log", 3) == 0){
+            stack[++top] = 'l';
+            i += 3;
+        }
+        else if (infix[i] == '('){
+            stack[++top] = '(';
+            i++;
+        }
+        else if (infix[i] == ')'){
+            while (top >= 0 && stack[top] != '('){
+                postfix[k++] = ' ';
+                postfix[k++] = stack[top--];
+         }
+            top--;
+            if (top >= 0 && (stack[top] == 's' || stack[top] == 'c' || stack[top] == 'l')){
+                postfix[k++] = ' ';
+                postfix[k++] = stack[top--];
+         }
+            i++;
+        }
+        else if (is_operator(infix[i])){
+            postfix[k++] = ' ';
+            while (top >= 0 && precedence(stack[top]) >= precedence(infix[i])){
+                postfix[k++] = stack[top--];
+                postfix[k++] = ' ';
+            }
+            stack[++top] = infix[i++];
+        }
+        else {
+            i++;
+        }
+    }
+
+    while (top >= 0) {
+        postfix[k++] = ' ';
+        postfix[k++] = stack[top--];
+    }
+
+    postfix[k] = '\0';
+}
+
+double evaluate_postfix(const char *postfix) {
+    double stack[MAX];
+    int top = -1;
+    int i = 0;
+    char num[MAX];
+
+    while (postfix[i] != '\0') {
+
+        if (postfix[i] == ' ') {
+            i++;
+            continue;
+        }
+
+        if ((postfix[i] >= '0' && postfix[i] <= '9') || postfix[i] == '.') {
+            int j = 0;
+            while ((postfix[i] >= '0' && postfix[i] <= '9') || postfix[i] == '.') {
+                num[j++] = postfix[i++];
+            }
+            num[j] = '\0';
+            stack[++top] = atof(num);
+        }
+        else {
+            if (postfix[i] == 's') {
+                stack[top] = sin(stack[top]);
+            }
+            else if (postfix[i] == 'c') {
+                stack[top] = cos(stack[top]);
+            }
+            else if (postfix[i] == 'l') {
+                stack[top] = log(stack[top]);
+            }
+            else if (postfix[i] == '^'){
+                stack[top] = stack[top] * stack[top];
+         }
+         else{
+               double b = stack[top--];
+               double a = stack[top--];
+
+               if (postfix[i] == '+') stack[++top] = a + b;
+               if (postfix[i] == '-') stack[++top] = a - b;
+               if (postfix[i] == '*') stack[++top] = a * b;
+               if (postfix[i] == '/') stack[++top] = a / b;
+         }
+         i++;
+      }
+   }
+    return stack[top];
+}
+

sk2/calculator.h

@@ -0,0 +1,13 @@
+#ifndef CALCULATOR_H
+#define CALCULATOR_H
+
+#define MAX 256
+
+void infix_to_postfix(const char *infix, char *postfix);
+double evaluate_postfix(const char *postfix);
+
+int precedence(char op);
+int is_operator(char c);
+
+#endif
+

sk2/main.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include "calculator.h"
+
+int main(){
+    char infix[MAX];
+    char postfix[MAX];
+
+    printf("Zadaj matematicky vyraz:\n");
+    fgets(infix, MAX, stdin);
+
+    infix_to_postfix(infix, postfix);
+
+    double vysledok = evaluate_postfix(postfix);
+
+    printf("Vysledok: %.2f\n", vysledok);
+
+    return 0;
+}
+