result/lab04_LitvinovaAnna/Task4/main.cpp

#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <windows.h>  // Äîáàâëåíî äëÿ ðàáîòû ñ êîäèðîâêîé

// Ìàêñèìóìû äëÿ áóôåðîâ (ñòåêîâûå ìàññèâû)
constexpr std::size_t kMaxFilenameLen = 260;
constexpr std::size_t kMaxQueryLen = 256;

// Íàáîð çàïðåùåííûõ ñèìâîëîâ äëÿ èìåíè ôàéëà (Windows)
constexpr const char* kForbidden = "*\"<>?|";

// Ïðîâåðêà âàëèäíîñòè èìåíè ôàéëà ïî ïðàâèëàì çàäàíèÿ
bool validate_filename(const char* name) {
    // çàïðåòíûå ñèìâîëû
    for (const char* p = kForbidden; *p; ++p) {
        if (std::strchr(name, *p)) {
            return false;
        }
    }

    // äâîåòî÷èå
    const char* colon = std::strchr(name, ':');
    if (colon) {
        if (colon != name + 1) return false;      // òîëüêî âòîðîé ñèìâîë
        if (!std::isalpha(static_cast<unsigned char>(name[0]))) return false;
        if (colon[1] != '\\') return false;       // çà äâîåòî÷èåì îáðàòíàÿ êîñàÿ
    }

    // ðàñøèðåíèå .txt (åñëè îíî åñòü)
    const char* dot = std::strrchr(name, '.');
    if (dot) {
        if (std::strlen(dot) != 4) return false;  // ".txt"
        char ext[5]{};
        // Èñïðàâëåíî: strncpy_s âìåñòî strncpy
        strncpy_s(ext, sizeof(ext), dot, 4);
        for (char& c : ext) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
        if (std::strcmp(ext, ".txt") != 0) return false;
    }

    return true;
}

// Äîáàâèòü .txt, åñëè òî÷êè íåò
void ensure_txt_extension(char* name, size_t bufferSize) {
    if (std::strrchr(name, '.') == nullptr) {
        // Èñïðàâëåíî: strcat_s âìåñòî strcat
        strcat_s(name, bufferSize, ".txt");
    }
}

// Ïîäñ÷èòàòü âõîæäåíèÿ ïîäñòðîêè sub â ñòðîêå text
int count_occurrences(const char* text, const char* sub) {
    int count = 0;
    const std::size_t len = std::strlen(sub);
    if (len == 0) return 0;

    const char* pos = text;
    while ((pos = std::strstr(pos, sub)) != nullptr) {
        ++count;
        pos += len;
    }
    return count;
}

int main() {
    // Íàñòðîéêà êîäèðîâêè êîíñîëè äëÿ ðóññêîãî òåêñòà
    SetConsoleOutputCP(1251);
    SetConsoleCP(1251);

    // 4.1: ââîä èìåíè ôàéëà (ñòåêîâûé áóôåð)
    char filename[kMaxFilenameLen]{};
    std::cout << "Ââåäèòå èìÿ ôàéëà: ";
    std::cin.getline(filename, kMaxFilenameLen);

    // 4.2: ïðîâåðêà êîððåêòíîñòè
    if (!validate_filename(filename)) {
        std::cout << "Íåêîððåêòíîå èìÿ ôàéëà\n";
        return 1;
    }

    // 4.3: äîáàâèòü .txt ïðè îòñóòñòâèè
    ensure_txt_extension(filename, sizeof(filename));
    if (!validate_filename(filename)) {
        std::cout << "Èìÿ íåêîððåêòíî ïîñëå äîáàâëåíèÿ .txt\n";
        return 1;
    }

    // 4.4: ÷òåíèå ôàéëà ïîëíîñòüþ â äèíàìè÷åñêèé áóôåð
    FILE* f = nullptr;
    // Èñïðàâëåíî: fopen_s âìåñòî fopen
    if (fopen_s(&f, filename, "rb") != 0 || !f) {
        std::cout << "Íå óäàëîñü îòêðûòü ôàéë: " << filename << "\n";
        return 1;
    }

    if (std::fseek(f, 0, SEEK_END) != 0) {
        std::cout << "Îøèáêà ïåðåìåùåíèÿ â êîíåö ôàéëà\n";
        std::fclose(f);
        return 1;
    }

    long sz = std::ftell(f);
    if (sz < 0) {
        std::cout << "Íå óäàëîñü îïðåäåëèòü ðàçìåð ôàéëà\n";
        std::fclose(f);
        return 1;
    }
    std::rewind(f);

    char* buffer = static_cast<char*>(std::malloc(static_cast<std::size_t>(sz) + 1));
    if (!buffer) {
        std::cout << "Íå óäàëîñü âûäåëèòü ïàìÿòü\n";
        std::fclose(f);
        return 1;
    }

    std::size_t read = std::fread(buffer, 1, static_cast<std::size_t>(sz), f);
    if (read != static_cast<std::size_t>(sz)) {
        std::cout << "Îøèáêà ÷òåíèÿ ôàéëà\n";
        std::free(buffer);
        std::fclose(f);
        return 1;
    }
    buffer[sz] = '\0';
    std::fclose(f);

    // 4.5: ââîä èñêîìîé ñòðîêè (ñòåêîâûé áóôåð)
    char query[kMaxQueryLen]{};
    std::cout << "Ââåäèòå ñòðîêó äëÿ ïîèñêà: ";
    std::cin.getline(query, kMaxQueryLen);

    // 4.6: ïîäñ÷¸ò âõîæäåíèé
    const std::size_t qlen = std::strlen(query);
    if (qlen == 0) {
        std::cout << "Ïóñòàÿ ñòðîêà ïîèñêà\n";
        std::free(buffer);
        return 1;
    }

    int hits = count_occurrences(buffer, query);
    std::cout << "×èñëî âõîæäåíèé \"" << query << "\": " << hits << "\n";

    // 4.7: îñâîáîæäåíèå ïàìÿòè
    std::free(buffer);
    return 0;
}