What's wrong with this program in C++ using an archive input?

Question

I have the folowing code in C++:

#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace std;

int main(int argc, char **argv)
{
    int N;
    string s;
    char str[100];
    scanf("%d",&N);

    for(int i=0; i<N; i++)
    {
        fflush(stdin);
        fgets(str,100,stdin);
        s = str;
        cout << s << endl;
    }

    return 0;
}

The code is save in an archive test.cpp.

Using the terminal on Linux Ubuntu for compile:

g++ -c hello.cpp
g++ -o hello hello.o

I have an archive test.in that will be the input:

5
God of War
Grand Theft Auto
The Smurfs
Final Fantasy
Call of Duty

Runing the command in terminal:

./test < test.in

The output will be:

rogerio@rogerio-Aspire-5741Z:~/Documentos$ ./teste < teste.in


God of War

Grand Theft Auto

The Smurfs

Final Fantasy

rogerio@rogerio-Aspire-5741Z:~/Documentos$

Because the line "Call of Duty" is jumped?

Compile with `g++ -Wall -g hello.cpp -o hello` and learn how to use the `gdb` debugger (e.g. start with `gdb hello`) — Basile Starynkevitch, Apr 05 '14 at 18:12
Using `fflush` on `stdin` is not defined. Search StackOverflow for "fflush stdin". — Thomas Matthews, Apr 05 '14 at 18:23
@Thomas - I learned something new today.... Its amazing what shows up as undefined. I would have thought it would degenerate to a simple `nop`. — jww, Apr 05 '14 at 18:51
I found a solution to my problem. Using 'scanf("%d\n",&N);' the five lines are read. hanks to all who helped!! — user3338417, Apr 05 '14 at 19:17

score 3 · Answer 1 · answered Apr 05 '14 at 18:37

3

The

scanf("%d",&N);

doesn't skip beyond end of line, therefore the first fgets(str,100,stdin); just reads the remainder of the line where 5 is given. Note the extra blank line in the output as you have posted it?

answered Apr 05 '14 at 18:37

laune

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What's wrong with this program in C++ using an archive input?

1 Answers1