c++对字符串进行切割

对inputstring进行切割，切分标志为字符串c,统计每种子串出现的次数，返回一个map对象。

map<string, int> split(string inputstring, string c) {
    vector<string> result;
    map<string, int> temp_map;
    string::size_type pos1 = 0, pos2 = 0;
    string temp;
    while (pos2 < inputstring.size()) {
        pos2 = inputstring.find(c, pos2);
        if (pos2 == -1) {
            while (pos1 <inputstring.size()) {
                if (isalpha(inputstring[pos1]))
                    temp += tolower(inputstring[pos1]);