C++ 为什么 getline() 只适用于我的函数的第一个实例？

Question

#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <cstdlib>

//These two functions work fine
std::vector<std::string> &split(const std::string &s, char delim, std::vector<std::string> &elems) {
    std::stringstream ss(s);
    std::string item;
    while (std::getline(ss, item, delim)) {
        if(!item.empty())
            elems.push_back(item);
    }
    return elems;
}
std::vector<std::string> split(const std::string &s, char delim) {
    std::vector<std::string> elems;
    split(s, delim, elems);
    return elems;
}

//I think this function is where the problem is
std::string& singleSplit(const std::string* s, char delim='[=10=]'){
    static std::string input=*s;
    static std::stringstream ss(*s);
    if(input!=*s){ss.str(*s);input=*s;}

    std::string item;

    if (std::getline(ss, item, delim)&&!item.empty())
        {std::cout<<item<<std::endl;return item;}

}
void setIntFrames(std::vector<std::string>& frames, std::vector<uint16_t>* Start, std::vector<uint16_t>* End)
{
    for(int i=0; i<frames.size(); i++)
    {
        Start->push_back(std::atoi((singleSplit(&frames[i],'-').c_str())));
        End->push_back(std::atoi((singleSplit(&frames[i],'[=10=]').c_str())));
    }//this loop works fine the first time it passes, but the second time it just pushes back 0's into my Start and End vectors
}


int main()
{
    std::string x="0000-1200,1201-2359";//sample string of what alloted time frames in a day would look like
    std::vector<std::string>timeFrames(split(x,','));
    std::vector<uint16_t>startTimes; std::vector<uint16_t>endTimes;
    setIntFrames(timeFrames, &startTimes, &endTimes);

    std::cout<<startTimes[1]<<std::endl<<endTimes[1]; 
//setIntFrames() didn't set these correctly, I don't know why
    return 0;
}

我正在尝试制作一个简单的日程安排程序。我正在处理将 main() 内部的字符串 x 转换为开始和结束时间的数组（在本例中为向量）。我尝试这样做的方式是首先将原始字符串拆分为多个字符串（由'，'分隔）然后放入向量时间帧中。下一步是拆分那些较小的字符串，将它们转换为整数，然后将它们放入 startTimes 向量或 endTimes 向量中。我在此步骤中使用了 setIntFrames，但我不明白为什么它只能设置第一个 timeFrame。

我很确定问题出在我的 singleSplit() 函数上，但我对 getline 和 stringstream 的了解不足以解决这个问题。感谢任何帮助。

Answer 1

这对我有用。我将传入的参数更改为引用，然后在使用后将它们推回。

#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <cstdlib>

//These two functions work fine
std::vector<std::string> &split(const std::string &s, char delim, std::vector<std::string> &elems) {
    std::stringstream ss(s);
    std::string item;
    while (std::getline(ss, item, delim)) {
        if(!item.empty())
            elems.push_back(item);
    }
    return elems;
}
std::vector<std::string> split(const std::string &s, char delim) {
    std::vector<std::string> elems;
    split(s, delim, elems);
    return elems;
}

//I think this function is where the problem is
void singleSplit(const std::string& s, char delim, std::string& first, std::string& second){

    std::stringstream ss(s);

    if (std::getline(ss, first, delim)){
    std::cout << "Found:" << first << '\n';
    }
    if (std::getline(ss, second)){
        std::cout << "Found:" << second << '\n';
    }

}
void setIntFrames(std::vector<std::string>& frames, std::vector<uint16_t>& Start, std::vector<uint16_t>& End)
{
    std::string first, second;
    for(int i=0; i<frames.size(); i++)
    {
        std::cout << frames[i] << '\n';
    singleSplit(frames[i], '-', first, second);
        Start.push_back(std::atoi(first.c_str()));
        End.push_back(std::atoi(second.c_str()));
    }//this loop works fine the first time it passes, but the second time it just pushes back 0's into my Start and End vectors
}


int main()
{
    std::string x="0000-1200,1201-2359";//sample string of what alloted time frames in a day would look like
    std::vector<std::string>timeFrames(split(x,','));
    std::vector<uint16_t>startTimes; std::vector<uint16_t>endTimes;
    setIntFrames(timeFrames, startTimes, endTimes);

    // std::cout<<startTimes[1]<<std::endl<<endTimes[1]; 
    for (int i = 0; i < startTimes.size(); ++i){
        std::cout << i << ':' << startTimes[i] << '\t' << endTimes[i] << '\n';
    }
//setIntFrames() didn't set these correctly, I don't know why
    return 0;
}

输出如下所示：

 $ a.out
0000-1200
Found:0000
Found:1200
1201-2359
Found:1201
Found:2359
0:0     1200
1:1201  2359

C++ 为什么 getline() 只适用于我的函数的第一个实例？

C++ why does getline() only work on the first instance of my function?

getline

c++11