Question

c++问题，ios::fail怎么用？

问题是这样的，创建复数类，重载流提取和插入运算符为友元函数，流提取运算符判断输入的数据是否合法，如果非法则置位ios::fail以知识输入不正确，需按以下格式输入3+8i，编写main函数测试输入输出

Answer 1

bool fail( ) const;
Return Value
true if rdstate
& (badbit|failbit)
is nonzero, otherwise false.

For more information on failbit, see ios_base::iostate.

Example
// basic_ios_fail.cpp
// compile with: /EHsc
#include <iostream>

int main( void )
{
using namespace std;
bool b = cout.fail( );
cout << boolalpha;
cout << b << endl;
}
Output
false
Requirements
Header: <ios>

Namespace: std