Задание 4. Написать программу для обработки текстового файла

lab04_4.cpp

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+#include <iostream>
+#include <fstream>
+#include <cstring>
+#include <cctype>
+
+// Êîíñòàíòû
+const size_t MAX_SIZE = 256;
+const char* separators = " \r\n,.!?:;()-";
+const char* forbidden_chars = "*\"<>|?";
+
+// Ôóíêöèÿ äëÿ ïðîâåðêè êîððåêòíîñòè èìåíè ôàéëà
+bool is_valid_filename(const char* filename) {
+    // Ïðîâåðêà íà çàïðåùåííûå ñèìâîëû
+    if (strpbrk(filename, forbidden_chars)) {
+        return false;
+    }
+
+    // Ïðîâåðêà íà äâîåòî÷èå
+    const char* colon_pos = strchr(filename, ':');
+    if (colon_pos && (colon_pos != filename + 1 || !isalpha(colon_pos[-1]) || colon_pos[1] != '\\')) {
+        return false;
+    }
+
+    // Ïðîâåðêà ðàñøèðåíèÿ
+    const char* dot_pos = strrchr(filename, '.');
+    if (dot_pos && strncmp(dot_pos, ".txt", 4) != 0 && strncmp(dot_pos, ".TXT", 4) != 0) {
+        return false;
+    }
+
+    return true;
+}
+
+// Ôóíêöèÿ äëÿ äîáàâëåíèÿ ðàñøèðåíèÿ .txt, åñëè åãî íåò
+void add_txt_extension(char* filename) {
+    const char* dot_pos = strrchr(filename, '.');
+    if (!dot_pos || strncmp(dot_pos, ".txt", 4) != 0) {
+        strcat(filename, ".txt");
+    }
+}
+
+int main() {
+    // Øàã 4.1: Çàïðîñèòü ó ïîëüçîâàòåëÿ èìÿ ôàéëà
+    char filename[MAX_SIZE];
+    std::cout << "Enter the filename: ";
+    std::cin.getline(filename, MAX_SIZE);
+
+    // Øàã 4.2: Ïðîâåðèòü êîððåêòíîñòü èìåíè ôàéëà
+    if (!is_valid_filename(filename)) {
+        std::cerr << "Invalid filename." << std::endl;
+        return 1;
+    }
+
+    // Øàã 4.3: Äîáàâèòü ðàñøèðåíèå .txt, åñëè åãî íåò
+    add_txt_extension(filename);
+
+    // Øàã 4.4: Çàãðóçèòü ñîäåðæèìîå òåêñòîâîãî ôàéëà â ïàìÿòü
+    std::ifstream file(filename, std::ios::binary | std::ios::ate);
+    if (!file) {
+        std::cerr << "Failed to open file." << std::endl;
+        return 1;
+    }
+
+    std::streamsize size = file.tellg();
+    file.seekg(0, std::ios::beg);
+
+    char* buffer = new char[size + 1];
+    if (!file.read(buffer, size)) {
+        std::cerr << "Failed to read file." << std::endl;
+        delete[] buffer;
+        return 1;
+    }
+    buffer[size] = '\0';
+    file.close();
+
+    // Øàã 4.5: Çàïðîñèòü ó ïîëüçîâàòåëÿ ñòðîêó
+    char search_string[MAX_SIZE];
+    std::cout << "Enter the string to search: ";
+    std::cin.getline(search_string, MAX_SIZE);
+
+    // Øàã 4.6: Ïîäñ÷èòàòü è âûâåñòè ÷èñëî âõîæäåíèé ñòðîêè â òåêñò ôàéëà
+    int count = 0;
+    const char* pos = buffer;
+    while ((pos = strstr(pos, search_string)) != nullptr) {
+        count++;
+        pos++;
+    }
+    std::cout << "The string \"" << search_string << "\" occurs " << count << " times in the file." << std::endl;
+
+    // Øàã 4.7: Îñâîáîäèòü âûäåëåííóþ ïàìÿòü
+    delete[] buffer;
+
+    return 0;
+}