C++ string功能补充（类型互转，分割，合并，瘦身）

int StringUtil::intFromString(string data)

{

    //NOTE atoi是非标准C函数

    return atoi(data.c_str());

}

string StringUtil::stringFromInt(int data)

{

    char tmp[11];

    memset(tmp,0,11);

    sprintf(tmp,"%10d",data);

    return string(tmp);

}

double StringUtil::doubleFromString(string data)

{

    double tmp;

    sscanf(data.c_str(),"%lf",&tmp);

    return tmp;

}

string StringUtil::stringFromDouble(double data)

{

    char tmp[21];

    memset(tmp,0,21);

    sprintf(tmp,"%20.3lf",data);

    return string(tmp);

}

float StringUtil::floatFromString(std::string data)

{

    float tmp;

    sscanf(data.c_str(),"%f",&tmp);

    return tmp;

}

std::string StringUtil::stringFromFloat(float data)

{

    char tmp[21];

    memset(tmp,0,21);

    sprintf(tmp,"%20.3f",data);

    return string(tmp);

}

bool StringUtil::boolFromString(std::string data)

{

    if(data.compare("true") == 0)

        return true;

    else

        return false;

}

std::string StringUtil::stringFromBool(bool data)

{

    if(data)

        return string("true");

    else

        return string("false");

}

vector<std::string> StringUtil::splitStringToArray(std::string source, std::string seperator)

{

    vector<string> result;

    if(!source.empty())

    {

        string::size_type begin = 0;

        string::size_type end = 0;

        unsigned int sepSize = seperator.size();

        while((end = source.find_first_of(seperator,begin))!=string::npos)

        {

            string item = source.substr(begin,end-begin);

            result.push_back(item);

            begin=end + sepSize;

        }

        //last item,注意如果最后是分割符，则最后的元素为空字符串

        if(begin <= source.size())

        {

            string item = source.substr(begin,source.size() - begin);

            result.push_back(item);

        }

    }

    return result;

}

std::string StringUtil::linkArrayToString(vector<std::string> array, std::string seperator)

{

    string result;

    if(array.size() > 0)

    {

        unsigned int limit = array.size() - 1;

        for(unsigned int i=0;i< limit;++i)

        {

            result+=array[i];

            result+=seperator;

        }

        result += array[limit];

    }

    return result;

}

map<std::string, std::string> StringUtil::splitStringToMap(std::string source, std::string primarySep, std::string secondarySep)

{

    vector<string> array = StringUtil::splitStringToArray(source,primarySep);

    vector<string> tmpArray;

    map<string,string> result;

    for(unsigned int i = 0; i< array.size();++i)

    {

        tmpArray = StringUtil::splitStringToArray(array[i],secondarySep);

        if(tmpArray.size() >= 2)

        {

            result[tmpArray[0]] = tmpArray[1];

        }

    }

    return result;

}

std::string StringUtil::linkMapToString(map<std::string, std::string> tmpMap, std::string primarySep, std::string secondarySep)

{

    vector<string> tmpArray;

    string tmpStr;

    map<string,string>::iterator it = tmpMap.begin();

    for(;it!=tmpMap.end();++it)

    {

        tmpStr = it->first+secondarySep+it->second;

        tmpArray.push_back(tmpStr);

    }

    return StringUtil::linkArrayToString(tmpArray,primarySep);

}

std::string StringUtil::trimFront(std::string data)

{

    unsigned int i = 0;

    for(;i<data.size()&&data.at(i)==' ';++i)

    {

    }

    if(i<data.size())

        return data.substr(i,data.size()-i);

    else

        return string("");

}

std::string StringUtil::trimBack(std::string data)

{

    int i = data.size()-1;

    for(;i>=0&&data.at(i)==' ';--i)

    {

    }

    if(i>=0)

        return data.substr(0,i+1);

    else

        return string("");

}

std::string StringUtil::trim(std::string data)

{

    string tmp = StringUtil::trimFront(data);

    return StringUtil::trimBack(tmp);

}