CLion won't print in console after scanf

Question

Console in CLion won't print line after scaning input, but in iTerm after compiling it all works perfectly. Code:

#include <stdio.h>
#include <stdlib.h>
int main() {
    char personName;
    printf("Hello, what is your name?\n");
    scanf("%s", personName);
    printf("Hello, %s\n", personName);
    return 0;
}

I just got this in CLion console:

Hello, what is your name?
Mike

Process finished with exit code 11

You need to allocate space for the string. `personName` is a single char, but you are trying to read a multi-character string into it. That leads to undefined behavior. — pstrjds, Nov 17 '17 at 23:55
Half of the tags were completely irrelevant. Pick one C or C++, but know that if this is intended to be C++, you're being educated from sources about 25 years out of date. — user4581301, Nov 17 '17 at 23:57
Undefined behaviour has undefined results. I doesn't work in iTerm. It merely LOOKS like it works. — user4581301, Nov 17 '17 at 23:58
Worthwhile reading so that next time you see Process finished with exit code 11 you know what it means: https://stackoverflow.com/questions/31103254/meaning-of-exit-code-11-in-c — user4581301, Nov 18 '17 at 00:01
I just add [50] at the end of char personName and that's a solution. Thank you everyone. :) — jovicbg, Nov 18 '17 at 00:01
It's ok for now, If you know how to help, please, not just looking for mistakes in question. @user4581301 — jovicbg, Nov 18 '17 at 00:05
No offence intended. It is OK for now. This is a common problem in C and not trivial to solve because you cannot easily change the size of an array based on the input. In C++, you use `std::string` and iostreams. `std::string name; std::cin >> name;` will work so long as you don't have a compound name like "Billy Bob". — user4581301, Nov 18 '17 at 00:12
@user4581301 Off by 1. With `add [50]`, that works until someone puts in a 50 character long name. — chux - Reinstate Monica, Nov 18 '17 at 03:06

Rahat Zaman · Answer 1 · 2017-11-18T03:12:45.950

1

You need to use an array for personName. The code will be,

#include <stdio.h>
#include <stdlib.h>
int main() {
    char personName[32];
    printf("Hello, what is your name?\n");
    if(scanf("%s", personName))
        printf("Hello, %s\n", personName);
    return 0;
}

edited Nov 18 '17 at 03:12

answered Nov 18 '17 at 00:04

Rahat Zaman

1,322
14
32

2

Using a length as short as 10, while an order of magnitude better than the question, is not 'safe'; it is far too easy to overflow. It would be best to use `char personName[32];` and `if (scanf("%31s", personName) == 1) printf("Hello, %s\n", personName);`. The different-by-one on the lengths is unfortunate but hallowed by history and enshrined in the standards. – Jonathan Leffler Nov 18 '17 at 00:21

CLion won't print in console after scanf

1 Answers1