std::getline 在接受多个字符串输入时忽略第一个字符，并且在不使用 cin.ignore() 时字符串下标超出范围

Question

when i use cin.ignore() i can take all inputs but i'm missing the first character of all strings after the first input.

If I don't use cin.ignore() I'm getting a string subscript goes out of range run time error

Here's the code for reference

std::vector<std::string> input;

for (int i = 0; i < 5; i++)
    {
        std::string lines;
        std::cin.ignore();
        std::getline(std::cin,lines,'\n');
        input.push_back(lines);
    }

Answer 1

What do you mean "getting a string subscript goes out of range run time error"? I comment out the code" std::cin.ignore(); ", the program run properly. The function getline will discard the char '\n'.

I test these codes you provided, if I comment out cin.ingnore, it run properly. Here is code:

#include<iostream>
#include<vector>
#include<string>
using namespace std;
int main() {
    std::vector<std::string> input;

    for (int i = 0; i < 5; i++)
    {
        std::string lines;
        //std::cin.ignore();
        std::getline(std::cin, lines, '\n');
        input.push_back(lines);
    }
    for (auto s : input) {
        cout << endl << s;
    }
}

Maybe you should examine your codes, and find if there are some other bugs.