字符串的输入问题（如果输入的字符串带有空格）

#include<iostream>
#include<string>
using namespace std;
int main()
{
char a[126];
cout<<"1 please input the str"<<endl;
cin>>a;
int n1=strlen(a);
cout<<"n1:"<<n1<<endl;
cout<<"str[]:"<<a<<endl;
system("pause");
return 0;
}

#include<iostream>
#include<string>
using namespace std;
int main()
{
string str;
cout<<"1 please input the str"<<endl;
cin>>str;
int n2=str.length();
cout<<"n2:"<<n2<<endl;
cout<<"string str:"<<str<<endl;
system("pause");
return 0;
}

#include<iostream>
#include<string>
using namespace std;
int main()
{
char str[126];
cout<<"3 please input the str"<<endl;
scanf("%s",str);
int n2=strlen(str);
cout<<"n2:"<<n2<<endl;
cout<<"string str:"<<str<<endl;
system("pause");
return 0;
}

#include<iostream>
#include<string>
using namespace std;
int main()
{
char str[126];
cout<<"3 please input the str"<<endl;
gets(str);
int n2=strlen(str);
cout<<"n2:"<<n2<<endl;
cout<<"string str:"<<str<<endl;
system("pause");
return 0;
}

综上，要想输入带' '空格的字符串，需要使用gets()函数才行， cin scanf 都不可以，会受到空格的影响。