Find index of last char in search string in string?

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  1. #1
    Programming Ninja In-T...
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    Question Find index of last char in search string in string?

    Hello.
    I want to see if one string contains another string, and if so, return the index of the last char of the search string in the source string.

    string::find() wont work for me because it returns the index of the first char of the search string, not the index of the last.

    Do I need to write my own function?

  2. #2
    C++ Witch laserlight's Avatar
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    Consider: using string::find(), you obtain the index of the first char found. Using string::length(), you obtain the length of the string being searched for. Add the them, subtract 1, and you get the index of the last char of the search string.
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  3. #3
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    Quote Originally Posted by laserlight View Post
    Consider: using string::find(), you obtain the index of the first char found. Using string::length(), you obtain the length of the string being searched for. Add the them, subtract 1, and you get the index of the last char of the search string.
    Ok, thanks.
    I wrote a quick function implementing this approach.

  4. #4
    Registered User jeffcobb's Avatar
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    Actually you wanted string::rfind() when you consider:
    Code:
    string strSearch = "foo";
    string strData = "stew-foo-foobar";
    int npos = strData.rfind(strSearch);
    if( npos != std::string::npos)
    {
        npos += strSearch.size();
    }
    or something like this. I just got home, its 111 degrees in the shade and I have since put my brain on a shelf.
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  5. #5
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    Quote Originally Posted by jeffcobb View Post
    Actually you wanted string::rfind() when you consider:
    Code:
    string strSearch = "foo";
    string strData = "stew-foo-foobar";
    int npos = strData.rfind(strSearch);
    if( npos != std::string::npos)
    {
        npos += strSearch.size();
    }
    or something like this. I just got home, its 111 degrees in the shade and I have since put my brain on a shelf.
    No, because I wasn't trying to find the last occurance of a string in a string. I wanted to find the first occurance of a string in a string, then get the index of the last character of that string in a string. Savvy?
    Besides, I already got it to work with laserlight's method.

  6. #6
    Registered User jeffcobb's Avatar
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    OK; you weren't specific and all I got was "string::find() won't work because it returns the first occurrance...". No biggie as long as you only have one instance of the search string and that's all you want...
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  7. #7
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    Quote Originally Posted by jeffcobb View Post
    OK; you weren't specific and all I got was "string::find() won't work because it returns the first occurrance...". No biggie as long as you only have one instance of the search string and that's all you want...
    Yeah, that's all I want, because I read a single-line enum, enum value by enum value (comma to comma). I then use the function mentioned to find the position of the last char in the enum value name of the line read from that contains 'enum'. And it works well.

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