FileC/FileWorkC/Source.c

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>

int read_in_file(float* coefficient, FILE* file) {
	char** buffer = malloc(sizeof(char) * 3);
	for (size_t i = 0; i < 3; i++)
	{
		buffer[i] = malloc(sizeof(char) * 100);
	}
	if (fscanf(file, "%s %s %s", buffer[0], buffer[1], buffer[2]) == 3) {
		for (size_t i = 0; i < 3; i++)
		{
			if (!check_str(buffer[i])) {
				coefficient[i] = atof(buffer[i]);
			}
			else {
				printf("Íåêêîðåêòíûé ââîä");
				return 1;
			}
		}
	}
	else {
		printf("Íåêêîðåêòíûé ââîä. ôàéëå äîëæíî áûòü 3 êîýôôèöèåíòà");
		return 1;
	}
	return 0;
}
int check_str(char* str) {
	int i = 0;
	int count_point = 0;
	if (str[0] == '.') {
		return 1;
	}
	if (str[0] == '-') {
		i++;
	}
	while (str[i] != '\0') {
		if ((str[i] >= 0x410 && str[i] <= 0x419) || !isdigit(str[i])) {
			if (str[i] == '.' && count_point <= 0) {
				count_point++;
			}
			else {
				return 1;
			}
		}
		i++;
	}
	return 0;
}

int count_coefficient(float* coefficient, float** coefficient_answer) {
	if (coefficient[1] == 0 && coefficient[2] == 0) {
		coefficient_answer[0] = 0;
		coefficient_answer[1] = 0;
		return 0;
	}
	else if (coefficient[1] == 0) {
		if (coefficient[2] * -1 / coefficient[0] < 0) {
			return 1;
		}
		else {

			(*coefficient_answer)[0] = sqrt(coefficient[2] * -1 / coefficient[0]);
			(*coefficient_answer)[1] = sqrt(coefficient[2] * -1 / coefficient[0]) * -1;
			return 0;
		}
	}
	else if (coefficient[2] == 0) {
		(*coefficient_answer)[0] = 0;
		(*coefficient_answer)[1] = coefficient[1] * -1 / coefficient[0];
		return 0;
	}
	else if (coefficient[0] == 0) {
		return 1;
	}
	else {
		float* temp_array = realloc((*coefficient_answer), sizeof(float) * 3);
		float D = pow(coefficient[1], 2) - 4 * coefficient[0] * coefficient[2];
		temp_array[0] = D;
		if (D < 0) {
			return 1;
		}
		else if (D == 0) {
			temp_array[1] = (coefficient[1] * -1) / (2 * coefficient[0]);
			*coefficient_answer = temp_array;
			return 2;
		}
		else {
			temp_array[1] = ((coefficient[1] * -1) + sqrt(D)) / (2 * coefficient[0]);
			temp_array[2] = ((coefficient[1] * -1) - sqrt(D)) / (2 * coefficient[0]);
			*coefficient_answer = temp_array;

			return 3;
		}
	}
}
int write_in_file(int result_code, float* coefficient_answer) {
	FILE* file_with_answer = fopen("answers.txt", "w");
	switch (result_code)
	{
	case 0:
		fprintf(file_with_answer, "Äàííîå óðàâíåíèå áûëî ðåøåíî áåç äèñêðèìèíàíòà\n");
		fprintf(file_with_answer, "Ïåðâûé êîðåíü - %.4f\nÂòîðîé êîðåíü - %.4f\n", coefficient_answer[0], coefficient_answer[1]);
		fclose(file_with_answer);
		break;
	case 1:
		fprintf(file_with_answer, "Óðàâíåíèå íå èìååò êîðíåé");
		fclose(file_with_answer);
		break;
	case 2:
		fprintf(file_with_answer, "äèñêðèìèíàíòà ðàâåí %.4f, ïîýòîìó ó óðàâíåíèÿ îäèí êîðåíü\nÊîðåíü - %.4f", coefficient_answer[0], coefficient_answer[1]);
		fclose(file_with_answer);
		break;
	case 3:
		fprintf(file_with_answer, "äèñêðèìèíàíòà ðàâåí %.4f\nÏåðâûé êîðåíü - %.4f\nÂòîðîé êîðåíü - %.4f", coefficient_answer[0], coefficient_answer[1],coefficient_answer[2]);
		fclose(file_with_answer);
		break;
	default:
		break;
	}
}
int main() {
	system("chcp 1251>null");
	FILE* file = fopen("coefficient.txt", "r");
	float* coefficient = malloc(sizeof(float) * 3);
	if (read_in_file(coefficient, file)) {
		return 1;
	}
	fclose(file);
	float* coefficient_answer = malloc(sizeof(float) * 2);
	int code = count_coefficient(coefficient, &coefficient_answer);
	write_in_file(code, coefficient_answer);
}