c++ - 如何在二进制文件中查找字符串？

Question

我想在二进制文件中找到一个特定的字符串“fileSize”。
找到该字符串的目的是获取该字符串旁边的 4 个字节，因为这 4 个字节包含我想要读取的数据大小。

二进制文件的内容如下:

同一个字符串在另一个位置:

另一个位置:

下面是将数据写入文件的函数:

void W_Data(char *readableFile, char *writableFile) {
    ifstream RFile(readableFile, ios::binary);
    ofstream WFile(writableFile, ios::binary | ios::app);

    RFile.seekg(0, ios::end);
    unsigned long size = (unsigned long)RFile.tellg();
    RFile.seekg(0, ios::beg);

    unsigned int bufferSize = 1024;
    char *contentsBuffer = new char[bufferSize];

    WFile.write("fileSize:", 9);
    WFile.write((char*)&size, sizeof(unsigned long));
    while (!RFile.eof()) {
        RFile.read(contentsBuffer, bufferSize);
        WFile.write(contentsBuffer, bufferSize); 
    }
    RFile.close();
    WFile.close();
    delete contentsBuffer;
    contentsBuffer = NULL;
}

此外，搜索字符串的函数:

void R_Data(char *readableFile) {
    ifstream RFile(readableFile, ios::binary);

    const unsigned int bufferSize = 9;

    char fileSize[bufferSize];
    while (RFile.read(fileSize, bufferSize)) {
        if (strcmp(fileSize, "fileSize:") == 0) {
            cout << "Exists" << endl;
        }
    }
    RFile.close();
}

如何在二进制文件中查找特定的字符串？

Answer 1

我想到使用 find()是搜索模式的简单方法。

void R_Data(const std::string filename, const std::string pattern) {
    std::ifstream(filename, std::ios::binary);
    char buffer[1024];

    while (file.read(buffer, 1024)) {
        std::string temp(buffer, 1024);
        std::size_t pos = 0, old = 0;

        while (pos != std::string::npos) {
            pos = temp.find(pattern, old);
            old = pos + pattern.length();
            if ( pos != std::string::npos )
                std::cout << "Exists" << std::endl;
        }
        file.seekg(pattern.length()-1, std::ios::cur);
    }
}