从c++问题中删除多余的空格

#include <iostream>
#include <string>

using namespace std;

string removeExtraSpaces(string str) {
    // 删除开头多余的空格
    size_t start = str.find_first_not_of(' ');
    if (start != string::npos) {
        str = str.substr(start);
    }
    
    // 删除结尾多余的空格
    size_t end = str.find_last_not_of(' ');
    if (end != string::npos) {
        str = str.substr(0, end + 1);
    }
    
    // 删除中间多余的空格
    size_t pos = str.find(' ');
    while (pos != string::npos) {
        size_t next = str.find_first_not_of(' ', pos);
        if (next == string::npos) {
            break;
        }
        
        str.replace(pos, next - pos, " ");
        pos = str.find(' ', pos + 1);
    }
    
    return str;
}

int main() {
    string input;
    cout << "请输入一个字符串：" << endl;
    getline(cin, input);
    
    string result = removeExtraSpaces(input);
    cout << "处理后的字符串为：" << endl;
    cout << result << endl;
    
    return 0;
}