初学者C ++-字符串比较

Question

I'm a C# programmer that recently wanted to delve into something lower level so last week started learning C++ but have stumbled on something I thought would be fairly simple.

I enter the following string into my program:

"this is a test this test" and would expect the wordStructList to contain a list of 4 words, with occurrences of "test" and "this" set to 2. When debugging however, the string comparison (I've tried .compare and ==) always seems to increasing the value of occurrences no matter whether the comparison is true.

eg currentName = "is" word = "this"

but occurrences is still been incremented.

#include "stdafx.h"

using std::string;
using std::vector;
using std::find;
using std::distance;

struct Word
{
    string name;
    int occurrences;
};

struct find_word : std::unary_function<Word, bool> 
{
    string name;
    find_word(string name):name(name) { }
    bool operator()(Word const& w) const 
    {
        return w.name == name;
    }
};

Word GetWordStruct(string name)
{
    Word word;

    word.name = name;
    word.occurrences = 1;

    return word;
}

int main(int argc, char argv[])
{
string s;
string delimiter = " ";
vector<string> wordStringList;

getline(std::cin, s);

do
{
    wordStringList.push_back(s.substr(0, s.find(delimiter)));
    s.erase(0, s.find(delimiter) + delimiter.length());

    if (s.find(delimiter) == -1)
    {
        wordStringList.push_back(s);
        s = "";
    }

} while (s != "");

vector<Word> wordStructList;

for (int i = 0; i < wordStringList.size(); i++)
{
    Word newWord;

    vector<Word>::iterator it = find_if(wordStructList.begin(), wordStructList.end(), find_word(wordStringList[i]));

    if (it == wordStructList.end())
        wordStructList.push_back(GetWordStruct(wordStringList[i]));
    else
    {
        string word(wordStringList[i]);

        for (vector<Word>::size_type j = 0; j != wordStructList.size(); ++j)
        {
            string currentName = wordStructList[j].name;

            if(currentName.compare(word) == 0);
                wordStructList[j].occurrences++;
        }
    }
}

return 0;
}

I hope the question makes sense. Anyone shed any light on this? I'm also open to any tips about how to make the code more sensible/readable. Thanks

Answer 1

The problem is the semicolon after this if statement:

if(currentName.compare(word) == 0);

The semicolon terminates the statement, so the next line

wordStructList[j].occurrences++;

is not part of the if statement any more and will always be executed.