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


//去掉收尾空格
string& ClearHeadTailSpace(string &str)
{
if (str.empty())
{
return str;
}

str.erase(0,str.find_first_not_of(" "));
str.erase(str.find_last_not_of(" ") + 1);
return str;
}


//去掉字符串中的全部空格
string& ClearAllSpace(string &str)
{
int index = 0;
if( !str.empty())
{
while( (index = str.find(' ',index)) != string::npos)
{
str.erase(index,1);
}
}

return str;
}


int main()
{
string str = "  123   456  789   ";

cout << ClearHeadTailSpace(str) << endl;
cout << ClearAllSpace(str) << endl;

system("pause");
return 0;
}
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原文链接：https://blog.csdn.net/yao_hou/article/details/78840723