C printf() not returning values

Question

I have a very simple C example program that does a crude count of characters words and spaces from input. The program compiles without error but when tested the program doesn't return any of the int variables via the print function. I am using VS2012 for coding and compiling. Stepping into the code shows that the values are being calculated correctly. Is there something wrong with my code or the compiler?

#include <stdio.h>

#define IN 1
#define OUT 0
/* count digits, white space, others */
main()
{
    int c, nl, nw, nc, state;

    state = OUT;
    nl = nw = nc = 0;
    while ((c = getchar()) != EOF){
        ++nc;

        if(c == '\n'){
            ++nl;
        }

        if (c == ' ' || c == '\n' || c == '\t'){
            state = OUT;
        } else if (state == OUT){
            state = IN;
            ++nw;
        }

    }

    printf("%d %d %d\n", nl, nw, nc);
}

Are you sure you have output generated to a valid log or window and are looking in the correct place for the output? Also, on *rare* occasions, output is not flushed, and you should flush explicitly when in doubt. Are you running this code from the command line? If so it should print. Otherwise if a GUI or something there is probably another mechanism for displaying results. — clearlight, Mar 27 '15 at 18:22
Ah, good point - can he see ANY printf() output in other words. Something I would have determined right at the outset if I were coding it. — clearlight, Mar 27 '15 at 18:25
@rlwheeler Run your program pressing Ctrl + F5. Also you have to press Enter before pressing Ctrl + z — Vlad from Moscow, Mar 27 '15 at 18:25
Works fine for me. Run it, type some stuff, press ctrl-z, see output. — Retired Ninja, Mar 27 '15 at 18:35
"Stepping into the code shows that the values are being calculated correctly" Minor: disagree about line count. IMO, if input was only "123" or "123\n", both would be 1 line. I would count lines if the _previous_ character was `'\n'` and initialize the previous variable with `'\n'. — chux - Reinstate Monica, Mar 27 '15 at 19:15
Note: In C, the 6 standard (C locale) "white-spaces" are `" \f\n\r\t\v"`. — chux - Reinstate Monica, Mar 27 '15 at 19:18

score 0 · Answer 1 · answered Mar 27 '15 at 18:32

0

It works if you run it with stdin coming from a file a.exe < test.txt. It works if you run it with stdin coming from the console on Linux. It does not work if you run it with stdin coming from the console on Windows.

It must be some sort of Windows console oddity.

answered Mar 27 '15 at 18:32

markgz

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Works perfectly well in a Windows console, ending with `Ctrl-z`, although the break has to be immediately after a newline. – Weather Vane Mar 27 '15 at 19:08
then it must have been some cygwin oddity – markgz Mar 27 '15 at 22:03
If using *bash*, then the usual Unix `ctrl-d` should work even under Windows. – hyde Apr 04 '15 at 15:45

score 0 · Answer 2 · edited May 23 '17 at 12:22

0

In order to see the actual output, start the debugger with Ctrl-F5. This will keep the console window open.

See this answer for more information.

edited May 23 '17 at 12:22

Community

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answered Mar 27 '15 at 18:34

Taylor Price

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DeltaProxy · Accepted Answer · 2015-03-27T18:29:08.963

-2

Your loop is permanent. Meaning it doesn't end.. so it doesn't reach the call of printf.

EOF is indicator that clearly doesn't work like that here. You must break the loop on a specific key. Like enter for instance, which character decimal representation is 13 for carriage return. 10 for NL.

edited Mar 27 '15 at 18:29

answered Mar 27 '15 at 18:27

DeltaProxy

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Why is his loop infinite? – Vlad from Moscow Mar 27 '15 at 18:28
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It ends if you produce `EOF`. – Anto Jurković Mar 27 '15 at 18:28
That isn't specified automatically. – DeltaProxy Mar 27 '15 at 18:31
1

@DeltaProxy What is not specified automatically? Can he press simply Ctrl+Z? – Vlad from Moscow Mar 27 '15 at 18:32
He didn't want to end the loop like that.Or didn't know how to print EOF. – DeltaProxy Mar 27 '15 at 18:33
1

@DeltaProxy Just why do you think EOF won't work? That's the normal way to detect end of input from stdin (like from any stream). – hyde Mar 27 '15 at 19:07

C printf() not returning values

3 Answers3