Remove punctuation from a String object

Edit a program to remove the punctuation marks from the string object. The string required to be entered into the program must contain punctuation, and the output is the string object after the punctuation is removed.

Eliminate punctuation

#include <iostream>
#include <string>
#include <cctype>
using namespace std;

int main()
{
　　string s, result_str;
　　bool has_punct = false;　//用于标记字符串中有无标点
　　char ch;　//输入字符串

　　cout << "Enter a string:" << endl;
　　getline(cin, s);　//处理字符串：去掉其中的标点

　　for (string::size_type index = 0; index != s.size(); ++index)
　　{
　　　　ch = s[index];

　　　　if (ispunct(ch))
　　　　　　has_punct = true;
　　　　else
　　　　　　result_str += ch;
　　}
　　if (has_punct)
　　　　cout << "Result:" << endl << result_str <<endl;
　　else
　　{
　　　　cout << "No punctuation character in the string?!" << endl;
　　　　return -1;
　　}

　　return 0;
}