C++, user input check for '\\0' stops at s

问题:

If the user inputs a sentence containing spaces the while loop stops at one of these spaces. Why is this happening? are '\0' and a space the same or did i do something else wrong?

int main ( )
{
    char user_input[200];
    cin>>user_input;
    int i=0;
    while(user_input[i]!='\0')
    {
        i++;
    }
    cout<<i;
    return 1;

}

Thanks everyone, I appreciate your help.

回答1:

\0 is the null terminating character with ASCII code 0. Space is another character with ASCII 32 i suppose. In fact you are doing this.

cin >> user_input;

It takes input till you press space or enter. So no space is present in your user_input string. Use this instead of cin.

cin.getline (user_input, 200, '\0') ;

回答2:

This is an issue with reading using >> into a char array. It splits at whitespace when tokenizing. Try printing user_input to screen to confirm this.

Using getline into a std::string is generally safer in this context (as mentioned by daknøk). And I assume the input is likely to be terminated by a carriage return?

std::string user_input;
std::getline( std::cin, user_input, '\n' );

回答3:

This is because your input stops reading when white space is entered. You can use

cin.unsetf(ios::skipws)

By default it is set to skip white spaces. With this you will get your desired result.