Question

我试图读取一个文本文件，以查找短语/句子（/ substring？）出现的次数。我目前正在做一个真正的躲避工作（见下面的代码），但正如你所看到的，它依赖于一些相当笨重的if语句。

我无权访问我在家中使用的文件，因此我使用了一个名为big.txt的文件并搜索了像＆＃这样的短语34;和＃34;暂时。

理想情况下，我希望能够搜索＆＃34;此错误代码1＆＃34;它返回它发生的次数。关于如何让我的代码以这种方式工作的任何想法都将非常有用！

int fileSearch(string errorNameOne, string errorNameTwo, string textFile) {

string output;                                  //variable that will store word from text file


ifstream inFile;                        
inFile.open(textFile);                          //open the selected text file

if (!inFile.is_open()) {
    cerr << "The file cannot be opened";
    exit(1);
}

if (inFile.is_open()) {                         //Check to make sure the file has opened correctly

    while (!inFile.eof()) {                     //While the file is NOT at the end of the file

        inFile >> output;                       //Send the data from the file to "output" as a string

        if (output == errorNameOne) {           //Check to look for first word of error code
            marker = 1;                         //If this word is present, set a marker to 1
        }

        else if (marker == 1) {                 //If the marker is set to 1,
            if (output == errorNameTwo) {       //and if the word matches the second error code...
                count++;                        //increse count
            }

            marker = 0;                         //either way, set marker to 0 again
        }
    }
}

inFile.close();                                 //Close the opened file

return count;                                   //Function returns count of error
}

Answer 1

鉴于你的短语每行只能出现一次并且数字跟在短语之后，你可以逐行读取文件并使用std :: string :: find（）看你的短语在某处在线。这将返回该短语的位置。然后，您可以在短语之后立即检查线路的其余部分，以测试1或0的数字。

此代码可能不完全符合您的要求（仍然不确定具体规格），但希望它应包含足够的示例，说明您可以采取哪些措施来实现目标。

// pass the open file stream in to this function along with the 
// phrase you are looking for and the number to check
int count(std::istream& is, const std::string& phrase, const int value)
{
    int count = 0;

    std::string line;
    while(std::getline(is, line)) // read the stream line by line
    {
        // check if the phrase appears somewhere in the line (pos)
        std::string::size_type pos = line.find(phrase);

        if(pos != std::string::npos) // phrase found pos = position of phrase beginning
        {
            // turn the part of the line after the phrase into an input-stream
            std::istringstream iss(line.substr(pos + phrase.size()));

            // attempt to read a number and check if the number is what we want
            int v;
            if(iss >> v && v == value)
                ++count;
        }

    }
    return count;
}

int main()
{
    const std::string file = "tmp.txt";

    std::ifstream ifs(file);

    if(!ifs.is_open())
    {
        std::cerr << "ERROR: Unable to open file: " << file << '\n';
        return -1;
    }

    std::cout << "count: " << count(ifs, "Header Tangs Present", 1) << '\n';
}

希望这有帮助。

在文本文件c ++中搜索短语

1 个答案: