C++文件 输入时数字中掺杂字母

//L7_F0_P3.cpp#include <iostream>#include <fstream>using namespace std;int main(){ifstream ifs("L7_F0_P1.txt");if( !ifs ) {cout << "Error opening file\n";return 1;}int number;while( ifs >> number ) { // reading all numbers – number by number andcout << number << endl; // writing them to the standard output}ifs.close();return 0;}

Question(b):

When ifs >> number is true, and when it is false?      

Answer(b):

ifs >> number is evaluated to true, when program correctly read a value of variable number (input
data could be interpreted as some value of the appropriate type). On the other hand ifs >> number
evaluates to false, when program cannot interpret the input data as a value that could be assigned
to variable number or the end of file was reached, or there were some error.

Question(c):

Modify L7_F0_P1.txt such that it looks as follows 463 859A203 20 (replace space between 859 and

203 with letter A). What is the output of our program and why?

Answer(c):

There will be the two numbers in the output, i.e., 463 and 859. Then the next attempt to read from
ifs results in ifs >> number evaluated to false and end of the while loop.