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2025-10-29 19:46:56 +01:00
commit d665218448
5 changed files with 544 additions and 0 deletions

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CMakeLists.txt Normal file
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cmake_minimum_required(VERSION 4.0)
project(calculator C)
set(CMAKE_C_STANDARD 23)
add_executable(calculator main.c
structures.h
stack.c
stack.h
)
target_link_libraries(calculator m)

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main.c Normal file
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#include <ctype.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "stack.h"
#include "structures.h"
int calculate_stack(const stack *output_queue);
int str_to_num(char *string);
int calculate(int a, int b, char op);
string get_expression(int argc, char *argv[]);
stack get_output_queue(const stack *tokenisedExpression);
int push_operator(char operatorToPush, stack *output_stack, stack *operator_stack);
bool stack_higher_precedence(char op, char stackOp);
stack split_into_tokens(string expression);
string get_slice(int a, size_t b, const char *expression);
bool validate_expression(const char *expression);
charResult validate_char(char c);
void validate_malloc(const void *p);
void throw_error(char *msg);
const char *OPERATORS[] = {"+-", "*/", "^", "()"};
int main(const int argc, char *argv[]) {
const string expression = get_expression(argc, argv);
if (expression.string == nullptr) return 0;
stack tokens = split_into_tokens(expression);
stack_print(&tokens, "Tokens");
stack output_queue = get_output_queue(&tokens);
printf("%d\n", calculate_stack(&output_queue));
stack_deinit(&output_queue);
stack_deinit(&tokens);
free(expression.string);
return 0;
}
int calculate_stack(const stack *output_queue) {
stack calculation_stack = stack_init(IntArray, output_queue->len);
for (size_t i = 0; i <= output_queue->i; i++) {
const stackData element = stack_get(output_queue, i);
if (element.ret_code == 1)
throw_error("Couldn't retrieve element from output queue for calculation stack push");
switch (validate_char(element.data.string[0]).type) {
case Digit:
const int n = str_to_num(element.data.string);
const int r = stack_push(&calculation_stack, (stackInput){.n = n}, false);
if (r == 1) throw_error("Failed to push number to calculation stack");
break;
case Operator:
const stackData aP = stack_pop(&calculation_stack);
const stackData bP = stack_pop(&calculation_stack);
if (aP.ret_code == 1 || bP.ret_code == 1) throw_error("Failed to pop numbers from calculation stack");
const int result = calculate(aP.data.n, bP.data.n, element.data.string[0]);
const int rSp = stack_push(&calculation_stack, (stackInput){.n = result}, false);
if (rSp == 1) throw_error("Error while trying to push result into calculation stack");
break;
case Invalid:
fprintf(stderr, "The following string is not valid part of expression: '%s'\n", element.data.string);
throw_error(nullptr);
}
}
const stackData res = stack_get(&calculation_stack, 0);
if (res.ret_code == 1) {
fprintf(stderr, "Calculation stack index should be at position 0 but is at %d!\n", calculation_stack.i);
throw_error(nullptr);
}
return res.data.n;
}
int str_to_num(char *string) {
char *endptr;
const int num = (int) strtol(string, &endptr, 10);
if (endptr == string || *endptr != 0x0) {
fprintf(stderr, "Failed to convert the '%s' string to number\n", string);
throw_error(nullptr);
}
return num;
}
// ReSharper disable once CppNotAllPathsReturnValue
int calculate(const int a, const int b, const char op) {
switch (op) {
case '+':
return a + b;
case '-':
return a - b;
case '*':
return a * b;
case '/':
return a / b;
case '^':
return (int) pow(a, b);
}
fprintf(stderr, "Operator '%c' is invalid\n", op);
throw_error(nullptr);
}
string get_expression(const int argc, char *argv[]) {
string ex = {.string = nullptr};
if (argc <= 1) return ex; // first argument is just program name
size_t len = 0;
for (size_t i = 1; i < argc; i++) {
len += strlen(argv[i]);
}
const size_t totalLen = len * sizeof(char) + 1; // +1 => \0 (0x0)
char *expression = malloc(totalLen);
validate_malloc(expression);
expression[0] = '\0'; // since the following will cat string, we need to set the end or rather start point
for (size_t i = 1; i < argc; i++) {
strlcat(expression, argv[i], totalLen);
}
if (validate_expression(expression)) {
ex.string = expression;
ex.len = totalLen;
} else {
free(expression);
}
return ex;
}
// we could not return anything and just send pointer to stack?
stack get_output_queue(const stack *tokenisedExpression) {
stack output_stack = stack_init(StringArray, tokenisedExpression->len);
stack operator_stack = stack_init(CharArray, tokenisedExpression->len);
for (size_t i = 0; i < tokenisedExpression->i; i++) {
const stackData token = stack_get(tokenisedExpression, i);
if (token.ret_code == 1) throw_error("Failed to retrieve token");
if (validate_char(token.data.string[0]).type == Operator) {
// do operator shit
const int ret = push_operator(token.data.string[0], &output_stack, &operator_stack);
if (ret == 1) throw_error("Failed to push operator");
} else {
// push number to output queue
stack_push(&output_stack, token.data, false);
}
}
// pop everything from operator to output stack
while (operator_stack.i >= 0) {
const stackData popOp = stack_pop(&operator_stack);
if (popOp.ret_code == 1) throw_error("Failed to retrieve operator from stack");
const int ret = stack_push(&output_stack, popOp.data, true);
if (ret == 1) throw_error("Failed to push operator to output");
}
stack_deinit(&operator_stack);
return output_stack;
}
// push operator to operator queue and
int push_operator(const char operatorToPush, stack *output_stack, stack *operator_stack) {
if (operatorToPush == '(') {
return stack_push(operator_stack, (stackInput){.ch = operatorToPush}, false);
}
if (operatorToPush == ')') {
for (stackData el = stack_pop(operator_stack); el.data.ch != '('; el = stack_pop(operator_stack)) {
if (el.ret_code == 1) return 1;
const int r = stack_push(output_stack, el.data, true);
if (r == 1) return 1;
}
return 0;
}
for (stackData lastStackOp = stack_get(operator_stack, operator_stack->i);
stack_higher_precedence(operatorToPush, lastStackOp.data.ch);
lastStackOp = stack_get(operator_stack, operator_stack->i)) {
if (lastStackOp.ret_code == 1) return 1;
const stackData opToPush = stack_pop(operator_stack);
if (opToPush.ret_code == 1) return 1;
const int r = stack_push(output_stack, opToPush.data, true);
if (r == 1) return 1;
}
return stack_push(operator_stack, (stackInput){.ch = operatorToPush}, true);
}
bool stack_higher_precedence(const char op, const char stackOp) {
return validate_char(stackOp).opPrecedence > validate_char(op).opPrecedence;
}
stack split_into_tokens(const string expression) {
stack tokenisedExpression = stack_init(StringArray, expression.len);
int lastOp = -1;
for (size_t i = 0; i < expression.len; i++) {
if (validate_char(expression.string[i]).type != Operator) continue;
const string slice = get_slice(lastOp, i, expression.string);
if (slice.string != nullptr) {
const int ret = stack_push(&tokenisedExpression, (stackInput){.string = slice.string}, false);
if (ret == 1) throw_error("Failed to push slice into stack");
}
const int ret = stack_push(&tokenisedExpression, (stackInput){.ch = expression.string[i]}, true);
if (ret == 1) throw_error("Failed to push current operator into stack");
lastOp = i;
}
return tokenisedExpression;
}
// todo fix edge case on beginning
string get_slice(int a, size_t b, const char *expression) {
const size_t len = b - abs(a) - 1;
if (len < 1) return (string){.string = nullptr};
const size_t total_len = len * sizeof(char) + 1;
char *slice = malloc(total_len);
validate_malloc(slice);
for (const size_t i = ++a; a < b; a++) {
// we don't track i separately but how much has a moved since we started creating the slice
slice[a - i] = expression[a];
}
return (string){slice, total_len};
}
bool validate_expression(const char *expression) {
for (const char *it = expression; *it != '\0'; it++) {
if (validate_char(*it).type == Invalid) return false;
}
return true;
}
charResult validate_char(const char c) {
if (isdigit(c)) return (charResult){Digit, 0};
for (int i = 0; i < sizeof(OPERATORS); i++) {
for (int j = 0; j < sizeof(OPERATORS[i]); j++) {
if (c == OPERATORS[i][j])
return (charResult){Operator, i};
}
}
return (charResult){Invalid, 0};
}
void validate_malloc(const void *p) {
if (p != NULL) return;
throw_error("Failed to allocate memory");
}
void throw_error(char *msg) {
if (msg != nullptr)
fprintf(stderr, "%s\n", msg);
exit(1);
}

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//
// Created by marto on 27. 10. 25.
//
#include <stdio.h>
#include <stdlib.h>
#include "stack.h"
#include <string.h>
stack stack_init(const DataType type, const int len) {
stack stack = {
.type = type,
.i = -1,
.len = len,
};
const size_t arrLen = len * sizeof(char);
switch (type) {
case StringArray:
stack.data.sarr = malloc(arrLen);
break;
case CharArray:
stack.data.carr = malloc(arrLen);
break;
case IntArray:
stack.data.narr = malloc(arrLen);
default:
fprintf(stderr, "Failed to recognise the DataType for Stack structure");
exit(1);
}
// ReSharper disable once CppSomeObjectMembersMightNotBeInitialized
return stack;
}
void stack_deinit(stack *stack) {
switch (stack->type) {
case StringArray:
clear_str_array(stack);
free(stack->data.sarr);
stack->data.sarr = nullptr;
break;
case CharArray:
free(stack->data.carr);
stack->data.carr = nullptr;
break;
case IntArray:
free(stack->data.narr);
stack->data.narr = nullptr;
break;
}
}
int stack_push(stack *stack, const stackInput input, const bool pushCharToString) {
if (stack->i >= stack->len - 1) return 1;
stack->i++;
switch (stack->type) {
case StringArray:
char *str;
// if we still push to array of strings but we're pushing single character as string
if (pushCharToString) {
str = malloc(sizeof(char) + 1);
str[0] = input.ch;
str[1] = 0x0;
} else {
str = malloc(strlen(input.string) * sizeof(char) + 1);
strcpy(str, input.string);
}
stack->data.sarr[stack->i] = str;
break;
case CharArray:
stack->data.carr[stack->i] = input.ch;
break;
case IntArray:
stack->data.narr[stack->i] = input.n;
}
return 0;
}
stackData stack_pop(stack *stack) {
if (stack->i == -1) return (stackData){.ret_code = 1};
stackInput returnData;
switch (stack->type) {
case StringArray:
returnData.string = stack->data.sarr[stack->i];
// todo might have to do malloc?
// todo ticking timebomb
break;
case CharArray:
returnData.ch = stack->data.carr[stack->i];
break;
case IntArray:
returnData.n = stack->data.narr[stack->i];
break;
}
stack->i--;
return (stackData){returnData, 0};
}
stackData stack_get(const stack *stack, const int n) {
if (stack->i == -1 || n >= stack->len) return (stackData){.ret_code = 1};
stackInput returnData;
switch (stack->type) {
case StringArray:
returnData.string = stack->data.sarr[stack->i];
break;
case CharArray:
returnData.ch = stack->data.carr[stack->i];
break;
case IntArray:
returnData.n = stack->data.narr[stack->i];
break;
}
return (stackData){returnData, 0};
}
void stack_print(const stack *stack, const char *name) {
printf("Printing stack %s:\n", name);
if (stack->i == -1) return (void) printf("NULL\n");
for (int i = 0; i <= stack->i; i++) {
const stackData el = stack_get(stack, i);
if (el.ret_code == 1) {
fprintf(stderr, "Invalid index\n");
exit(1);
}
printf("[%d]: ", i);
switch (stack->type) {
case StringArray:
printf("'%s'", el.data.string);
break;
case CharArray:
printf("'%c'", el.data.ch);
break;
case IntArray:
printf("'%d'", el.data.n);
break;
}
printf("\n");
}
printf("\n");
}
static void clear_str_array(const stack *stack) {
for (size_t i = 0; i < stack->len; i++) {
free(stack->data.sarr[i]);
stack->data.sarr[i] = nullptr;
}
}

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//
// Created by marto on 27. 10. 25.
//
#ifndef CALCULATOR_STACK_H
#define CALCULATOR_STACK_H
typedef enum {
StringArray,
CharArray,
IntArray,
} DataType;
typedef struct {
DataType type;
union {
char **sarr;
char *carr;
int *narr;
} data;
// if i >= len, the program's guardrails have failed
int i, len;
} stack;
typedef union {
char ch;
char *string;
int n;
} stackInput;
typedef struct {
stackInput data;
int ret_code;
} stackData;
stack stack_init(DataType type, int len);
void stack_deinit(stack *stack);
int stack_push(stack *stack, stackInput input, bool pushCharToString);
stackData stack_pop(stack *stack);
stackData stack_get(const stack *stack, int n);
void stack_print(const stack *stack, const char *name);
static void clear_str_array(const stack *stack);
#endif //CALCULATOR_STACK_H

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//
// Created by marto on 25. 10. 25.
//
#ifndef CALCULATOR_STRUCTURES_H
#define CALCULATOR_STRUCTURES_H
typedef enum {
Digit,
Operator,
Invalid,
} charType;
typedef struct {
charType type;
size_t opPrecedence;
} charResult;
typedef struct {
char *string;
int len;
} string;
#endif //CALCULATOR_STRUCTURES_H