关于#c++#的问题：编译器报错：21 31 [Error] 'stoi' was not declared in this scope

Question

#stoi函数

#include<bits/stdc++.h>
using namespace std;

bool isprime(int n){
    if(n==0 || n==1)
        return false;
    for(int i = 2; i*i <= n; i++){
        if(n%i == 0)
            return false;
    }
    return true;
}

int main(){
    int l;
    int k;
    string s;
    cin>>l>>k>>s;
    
    for(int i = 0; i <= l-k; i++){
        int num = stoi(s.substr(i,k));
        if(isprime(num)){
            cout<<s.substr(i,k);
            return 0;
        }
    }
    cout<<"404";
    return 0;

} 

编译器报错：21 31 [Error] 'stoi' was not declared in this scope

Answer 1

添加#include <string.h>的头文件或者#include < cstring>的头文件