for_each

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

void biggies(vector<string> &words,ostream &os=cout,char c=' '){
    for_each(words.begin(),words.end(),[&os,c](const string &s){os<<s<<c;});

}
int main(){
    vector<string> v={"a","b","c"};
    biggies(v);
}

输出

a b c