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I am working on an algorithm, and I am asked to print "QUIT" when there is no more input to the program.

I am using 

char c;
while(c = getchar()){...}

because I need to look for '\n' characters and numbers.

So I copy the sample input and paste it on my program's to test it, but it keeps waiting for another input and therefore I get a time limit exceeded when I submit it.

PS: I can't use multithreading.

Carlos
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  • How do you know if there is more input? I might just consider pressing another key if you just wait another second. – Bo Persson Feb 18 '17 at 22:31

3 Answers3

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You can stop when getchar() returns EOF, like this:

int c;
while ((c = getchar()) != EOF) {...}

Note that c needs to be declared an int, not a char.

To make your program more C++-like, use operator >> instead of getchar in a loop, like this:

char c;
while (cin >> c) {...}
Sergey Kalinichenko
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getchar() returns an int, not a char. In particular, it returns EOF on end of file, and EOF is typically -1. So if you store that in a char, it will never compare equal to EOF.

int c;
while ((c = getchar()) != EOF) {
Waxrat
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Are you reading in from a file? If so, getchar() will return EOF: http://www.cplusplus.com/reference/cstdio/getchar/

so

    int c=getchar();
    while (c != EOF) {...}

should work.

MJErrelis-Phillips
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    You're on the right track, but this code snippet doesn't change the value of `c`. You need to either add `c = getchar();` before the end of the loop body or change the `while` statement to `while ((c = getchar()) != EOF)`. – Pete Becker Feb 18 '17 at 22:48
  • Thanks for that. I just assumed that he would update the variable at the end of the loop, but it's always good to remember that sort of thing. – MJErrelis-Phillips Apr 08 '17 at 00:53