在较长字符串中查找字符串

问题描述

您好，



我目前有一个文件名，我希望在其中搜索某个字符串，如果有的话，那么我希望根据具体的任务做什么我发现子串。



示例：



testDir / ham / test1.1

testDir / ham / test2.2

testDir / spam / test3.3

testDir / spam / test4.4



假设文件名存储为strFilename中的字符串。如果我想分开HAM和SPAM文件夹，我能使用strFilename.find（/ ham /）吗？到目前为止，在我的代码中，使用它只返回除了我想要的东西。



代码：

Hello,

I currently have a filename that I wish to search for a certain string within, if so, then I wish to do specific tasks based on what substring I found.

Example:

testDir/ham/test1.1
testDir/ham/test2.2
testDir/spam/test3.3
testDir/spam/test4.4

Let's say the filename is stored as a string in "strFilename". Would I be able to use strFilename.find("/ham/") if I wanted to seperate out the HAM and SPAM folders? So far, in my code, using this only returns everything except what I want.

Code:

<pre>int main(int argc, char* argv[] ) {

    int wordCount;
    int fileStrCount;
    int hamCount;
    int spamCount;

    set<string> seenWords;
    map<string, int> ham;
    map<string, int> spam;



    if( argc < 2 ) {
        cout <<  "ERROR: Must have atleast one filename! \n";
    }
    //The user gives a path to a directory containing "index"
    //File is used to store filename and fList stores them
    string files = "";
    vector<string> fList;

    //Storing full path of directory to later add /index
    string pathToDir = argv[1];
    string pathToIndex = pathToDir + "index";
    ifstream dirIndex( pathToIndex );

    //Push back all filenames within index to fList
    while( getline( dirIndex, files ) ) {
        fList.push_back( files );
    }

    string thirdWord = "";




    //Iterate through filenames and open them
    for(unsigned x = 0; x < fList.size(); x++) {
        string goHere = pathToDir + fList[x];
        ifstream fileToOpen( goHere );
        if( !fileToOpen.is_open() ) {
            cout << "Error: " << goHere << " cannot open!\n";
            return -1;
        }

        //Ignore first two lines
        fileToOpen.ignore( numeric_limits<streamsize>::max(), '\n' );
        fileToOpen.ignore( numeric_limits<streamsize>::max(), '\n' );
        cout << endl << goHere << endl;

        if( goHere.find("/ham/") == true ) {
        while( getline( fileToOpen, thirdWord, ' ' ) ) {
            ++ham[thirdWord];
            ++hamCount;
            wordCount++;
        }
    } else {
            while(getline(fileToOpen, thirdWord, ' ') ) {
            ++spamCount;
            ++spam[thirdWord];
            wordCount++;
            }
           }

        cout << "Total Words In File: " << fileStrCount << endl;

        fileToOpen.close();
        fileToOpen.clear();




    }
    cout << endl << endl << endl << "HAM MAP\n";
    for(auto elem : ham)
    {
        cout << elem.first << " " << elem.second << "\n";
    }

     cout << endl << endl << endl << "SPAM MAP\n";
    for(auto elem : spam)
    {
        cout << elem.first << " " << elem.second << "\n";
    }



}

主要关注点：

if( goHere.find("/ham/") == true ) {
        while( getline( fileToOpen, thirdWord, ' ' ) ) {
            ++ham[thirdWord];
            ++hamCount;
            wordCount++;
        }
    } else {
            while(getline(fileToOpen, thirdWord, ' ') ) {
            ++spamCount;
            ++spam[thirdWord];
            wordCount++;
            }
           }

我的尝试：



我试过调查str :: substr（）但这不是我想要的。

What I have tried:

I've tried looking into str::substr() but that isn't what I want either.

推荐答案

Quote：

返回值

第一个字符的位置第一场比赛。

如果没有找到匹配项，该函数返回string :: npos。

Return Value
The position of the first character of the first match.
If no matches were found, the function returns string::npos.

所以你必须将你的代码更改为：

So you have to change your code to:

if( goHere.find("/ham/") != string::npos )

这篇关于在较长字符串中查找字符串的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！