从cmd获取到的字符串多了\r\r\n,想把其替换掉，经查string.replace并不具备将字符串中，某个字符串，所有都替换功能，分析原因可能是情况太多了，例如：

此博客自己写的replace_all

用此函数，测试普通字符串，无问题，可正常替换；

仔细测试，bug出现：

目的：替换掉以下字符串中间的\r\r\n为空（等同过滤），正确输出：

目的字符串：00:50:56:C0:00:08MACAddress=01:50:56:C0:00:08MACAddress=02:50:56:C0:00:08

原字符串：00:50:56:C0:00:08\r\r\n\r\r\n\r\r\nMACAddress=01:50:56:C0:00:08\r\r\n\r\r\n\r\r\nMACAddress=02:50:56:C0:00:08

调用博客中函数结果：只替换了一处。

分析：普通替换  新值长度至少为1

                         多-------少    1234-----=534（12替换为5）//replace_all(“1234”, “12”, “5”)

                          少--------多    1234--------125634（2替换为256）//replace_all(“1234”, “2”, “256”)

                          以上新的替换值长度至少为1

          特殊替换： 新值为空，长度为0   

                             1\n\r2---------12（\n\r替换为空后，长度由4变成2）//replace_all(“1\n\r2”, “\n\r”, “”)；

                             新的替换值长度为0（空），此时以上博客函数，对大小判断表现出不严谨，经仔细斟酌修改如下：

//替换1 全部替换1次  12212 替换12为21------>21221

string& replace_all_distinct(string& str, const string& old_value, const string& new_value)
{
	string::size_type pos=0;
	while((pos=str.find(old_value,pos))!= string::npos)
	{
		str=str.replace(pos,old_value.length(),new_value);
		if(new_value.length()>0)
		{
			pos+=new_value.length();
		}
	}
	return str;

}

//替换2  循环替换，替换后的值也检查并替换 12212 替换12为21----->22211
string& replace_all(string& str, const string& old_value, const string& new_value)
{
		string::size_type pos=0;
		while((pos=str.find(old_value))!= string::npos)
		{
			str=str.replace(str.find(old_value),old_value.length(),new_value);
		}
		return str;
}

每次都从头查找替换，此问题解决！

警示：若用开源函数务必仔细测试，重在思路，而不是照搬，灵活运用才能游刃有余，谨慎测试 免除后患！

//************************************
// Method:        ReplaceStringInStd
// Describe:        使用指定子串替换字符串中的字符串，如果要替换的字符串为空，则移除原序列中的指定子串
// FullName:      ReplaceStringInStd
// Access:          public 
// Returns:        std::string
// Returns Describe:    返回替换操作后的字符串副本
// Parameter:    std::string strOrigin      ；原字符串
// Parameter:    std::string strToReplace   ；需要替换的字符换
// Parameter:    std::string strNewChar     ；替换后的字符换，当该字符串为空时，该函数的功能变成
//************************************
std::string ReplaceStringInStd(std::string strOrigin, std::string strToReplace, std::string strNewChar)
{
    std::string strFinal = strOrigin;
    if (strFinal.empty())
    {
        return strFinal;
    }

    if (strNewChar.empty())
    {
        size_t pos = std::string::npos;

        // Search for the substring in string in a loop untill nothing is found
        while ((pos = strFinal.find(strToReplace)) != std::string::npos)
        {
            // If found then erase it from string
            strFinal.erase(pos, strToReplace.length());
        }
    }
    else
    {
        for (std::string::size_type pos(0); pos != std::string::npos; pos += strNewChar.length())
        {
            pos = strFinal.find(strToReplace, pos);
            if (pos != std::string::npos)
                strFinal.replace(pos, strToReplace.length(), strNewChar);
            else
                break;
        }
    }
    return   strFinal;
}

#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
/*
* Erase First Occurrence of given  substring from main string.
*/
void eraseSubStr(std::string &mainStr, const std::string &toErase)
{
    // Search for the substring in string
    size_t pos = mainStr.find(toErase);
    if (pos != std::string::npos)
    {
        // If found then erase it from string
        mainStr.erase(pos, toErase.length());
    }
}
/*
* Erase all Occurrences of given substring from main string.
*/
void eraseAllSubStr(std::string &mainStr, const std::string &toErase)
{
    size_t pos = std::string::npos;
    // Search for the substring in string in a loop untill nothing is found
    while ((pos  = mainStr.find(toErase) ) != std::string::npos)
    {
        // If found then erase it from string
        mainStr.erase(pos, toErase.length());
    }
}
/*
* Erase all Occurrences of all given substrings from main string using C++11 stuff
*/
void eraseSubStrings(std::string &mainStr, const std::vector<std::string> &strList)
{
    // Iterate over the given list of substrings. For each substring call eraseAllSubStr() to
    // remove its all occurrences from main string.
    std::for_each(strList.begin(), strList.end(), std::bind(eraseAllSubStr, std::ref(mainStr), std::placeholders::_1));
}
/*
* Erase all Occurrences of all given substrings from main string using Pre C++11 stuff
*/
void eraseSubStringsPre(std::string &mainStr, const std::vector<std::string> &strList)
{
    // Iterate over the given list of substrings. For each substring call eraseAllSubStr() to
    // remove its all occurrences from main string.
    for (std::vector<std::string>::const_iterator it = strList.begin(); it != strList.end(); it++)
    {
        eraseAllSubStr(mainStr, *it);
    }
}
int main()
{
    std::string str = "Hi this is a sample string is for is testing is.";
    eraseAllSubStr(str, "this");
    std::cout << str << std::endl;
    eraseSubStringsPre(str, { "for", "is", "testing" });
    std::cout << str << std::endl;
    return 0;
}

string自带replace()方法并没有实现这一功能，需要借助<algorithm>中的replace()。

比如，我在资源管理器地址栏直接赋值地址后，输入给某一string变量，程序中使用这一地址前，首先需要将反斜杠替换为正斜杠，程序如下：

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;
void main() {
    cout << "输入地址：";
    string dir;
    getline(cin, dir);
    cout << endl << dir << endl;
    replace(dir.begin(), dir.end(), '\\', '/');
    cout << dir << endl;	
}