如何在C++中查找字符串中的子字符串的發生次數和位置

Question

我正在努力查找一個字符串中子字符串的位置數。 以下代碼僅爲我提供了字符串中子字符串的起始位置。 請幫幫我。

void Search(std::string SubString, vector<string> index) 
{ 
    vector<string>::const_iterator cii; 
    string temp; 
    bool found = false; 
    unsigned find = 0; 
    for(cii = index.begin(); cii != index.end(); cii++) 
    { 
     temp = *cii; 
     find = temp.find(SubString); 
     if(find != std::string::npos)//running.find() 
     { 
      cout << find << endl; 
      cout << *cii << endl; 
      found = true; 
     } 
     else 
     { 
      if((cii == index.end()) && found) 
      { 
       cout << "Not found\n"; 
       found = false; 
      } 
     } 
    } 
} 

int main() 
{ 
    vector<string> index; 
    ifstream myReadFile; 
    string str, running; 
    myReadFile.open("example.txt"); 
    char output[100]; 
    if (myReadFile.is_open()) 
    { 
     while (!myReadFile.eof()) 
     { 
      while(std::getline(myReadFile, str)) 
      { 

       index.push_back(str); 
      } 
     } 
    } 

    while(running != "END") 
    { 
     cout << "To Quit type:- END\n"; 
     cin >> running; 
     if(running == "END") 
     {break;} 
     else 
     { 
      Search(running, index); 
     } 

    } 

    myReadFile.close(); 
    return 0; 
} 

Answer 1

看一看std::string::find reference。 Find有第二個參數，搜索開始的位置。因此，只要將查找作爲第二個參數放到循環中，直到查找返回std :: string :: npos。沿線的東西：

int startpos = 0; 
int finds = 0; 
while ((startpos = yourstring.find(substring, startpos)) != std::string::npos) 
    ++finds; 

Answer 2

最後我做到了。 我對Search()函數做了些許修改。 找到下面的代碼。

void Search(std::string SubString, vector<string> index) 
{ 
    vector<string>::const_iterator cii; 
    string temp; 
    bool found = false; 
    unsigned find = 0; 
    static int n = 0; 
    for(cii = index.begin(); cii != index.end(); cii++) 
    { 
     temp = *cii; 
     std::string ::size_type pos = 0; 
     while((pos = temp.find(SubString, pos)) 
       != std::string::npos) 
     { 
      n++; 
      pos += SubString.size(); 
      cout << pos << " "; 
     } 
     if(n) 
     { 
     cout << " \n "; 
     cout << *cii << endl; 
     found = true; 
     } 
     else 
     { 
      if((cii == index.end() - 1) && !found) 
      { 
       cout << "Not found\n"; 
       found = false; 
      } 
     } 
     n = 0; 
    } 

}