c++ - 在 C++ 中使用 String 类的 .substr 获取无效参数

Question

我正在尝试使用 Eclipse 通过 C++ 中的以下函数测试字符串输入是否合法:

#include <string>

bool testLegal::checkData(std::string &input, int &reg) {

    //test to see if pitchnames are legal

    std::string toneClasses = "CDEFGAB";
    std::string accidentals = "#b";
    std::string toTest;

    try {
        //TEST 1 IS the pitch name legal?
        toTest = input.substr(0, 1);
        if (_isLegal(toTest, toneClasses) == false)
            throw dataClean(2, "The pitch name you entered is illegal. Please correct it!");

        //TEST 2 to see if there is a second character in the pitch name and whether it is a sharp or flat
        toTest = input.substr(1);
        if (input.length() == 2 && _isLegal(toTest, accidentals) == false)
            throw dataClean(3, "The second character in the pitch name must be a sharp or flat");

    } catch (const cExceptions& e) {    
        throw dataClean(4, "There is an error in the data you inputed. Please re-enter");
    }
    return true;
}

但是，关于 .substr 的参数，我收到了“无效参数”错误。我尝试了各种解决方案但没有成功。奇怪的是，该函数在 Netbeans 和 Codelite 中运行都没有任何问题。如果有任何想法是如何解决这个问题，我将不胜感激。感谢期待...

Answer 1

使用 NDK 时，我在 Eclipse 上遇到了类似的子字符串问题。我必须将整数转换为 string::size_type

string twoLetters = hexStr.substr((string::size_type)i,(string::size_type)2);