c++ - c++问题中的substr

Question

当我尝试执行程序时，第一次迭代的输出符合预期。但是对于第二次迭代，out 并没有按预期出现......

int main(){
        string insertBuffer;
        string valSep;
        valSep = ":";
        string configParamSep = "\r\n";
        int configParamSepSize = 2;
        string configParam;
        string::size_type mCPos = 0;
        string::size_type mCBeginPos = 0;
    int finished = 0;
    string one = "hai: yes";
    string two = "tension: no"; 
        insertBuffer = one + "\r\n" + two + "\r\n";

    cout<<"OUTPUT:"<<"\n";

        while (!finished){
                if( !(mCBeginPos >= insertBuffer.length()) && ((mCPos = insertBuffer.find(valSep,mCBeginPos)) != string::npos)){
                        configParam = insertBuffer.substr(mCBeginPos,mCPos);
                }else{
                        finished = 1;
                        break;
                }
        cout<<configParam<<"\n";
                mCBeginPos = mCBeginPos + insertBuffer.find(configParamSep,mCBeginPos) + configParamSepSize;
    }

    return 0;
}

输出:

hai
tension: no

但预期的输出是:-

hai
tension

知道为什么会这样吗？

Answer 1

basic_string<CharType, Traits, Allocator> substr(
    size_type _Off = 0,
    size_type _Count = npos
) const;

第二个参数不是结束索引

一个简单的修复:configParam = insertBuffer.substr(mCBeginPos,mCPos - mCBeginPos);