A question from beginner.

[LucianusChen]

Hi guys, I am new to C++ and got a problem with these codes below.

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

int main() {
    int n;
    char a[11];
    int i;

    cin>>n;

    while (n--) {
        cin.getline(a,11);
        cout<<strlen(a)<<endl;
    }
}

When i ran it, i got a unexpected "0" immediately after input n.

[VictorN]

What is the value of n in your test?
And BTW, have a look at this example.

[2kaud]

[When posting code, please use code tags so that the code is readable. Select Go Advanced, select the inserted formatted code and click '#']

[2kaud]

This is due to stream extraction (>>) and getline working in slightly different ways.

>> ignores leading white space (space, tab, newline) before the extraction and extracts up to white space but doesn't extract trailing white space.

getline() is the opposite. It doesn't ignore leading white space, but does extract the trailing delimiter (which is \n by default).

So if you say enter 2 for n, what you really enter is 2 then \n (new line)

>> extracts the 2 but leaves the \n

getline() then extracts the remaining \n which terminates it and as it hasn't extracted any data, the length of the extracted is 0 - as reported. n is decremented by 1 so is now 1. The getline() again wants input. There is none present so it waits for the input and things work now as probably expected.

The fix is to extract the remaining white space left by the >> by using .ignore (). See http://www.cplusplus.com/reference/i...stream/ignore/

Consider:

#include <iostream>
#include <cstring>
#include <limits>
using namespace std;

int main() {
	int n;

	cin >> n;
	cin.ignore(numeric_limits<streamsize>::max(), '\n');

	while (n--) {
		char a[11];

		cin.getline(a, 11);
		cout << strlen(a) << endl;
	}
}

[LucianusChen]

What is the value of n in your test?
And BTW, have a look at this example.

i put 3...and it only showed the first 2 results.

Thank you.

[LucianusChen]

Thank you so much.....you've been a huge help. i will go check how to use cin.ignore().