Codeforces compiler shows a different output than Code::Blocks (Question 282A - Bit++)

Question

I've been trying different compilers available on the Codeforces submission page but none of the different compilers is giving an output such as Code::Block's

Problem link: https://codeforces.com/problemset/problem/282/A

Here is my code:

#include <stdio.h>
#include <string.h>

int main() {
int count = 0, i = 0, final;
int x = 0;
char strg[3];

scanf("%d", &count);

for (i = 0; i < count; i++){
    scanf("%s", &strg[0], &strg[1], &strg[2]);
    if ((strcmp(strg,"x++") == 0) || (strcmp(strg,"++x") == 0)){
        x = x+1;
    } if ((strcmp(strg,"x--") == 0) || (strcmp(strg,"--x") == 0)){
        x = x-1;
    }
}
printf("%d", x);

}

Submission page output: "wrong answer 1st numbers differ - expected: '1', found: '0'" However, Code::Blocks prints the correct value which is "1".

Codeforces submission:

Program running output:

A C string is limited by a final end-of-string character '\0'. But since your variable has only space for 3 characters, the used test checker might put anything after the third character. -- Another quirk: Why are you providing three target arguments for just one format specifier at your call of scanf()? Additionally, you should check its return value. — the busybee
– the busybee, Commented Jun 21, 2020 at 17:04
I checked the return value and it's just the same as the printf() output, could you please further clarify what I should do? — Mina Basem
– Mina Basem, Commented Jun 21, 2020 at 19:58
Well, the return value of printf() has a completely different meaning than the return value of scanf(). Please read its documentation. -- Another thing to consider: Are you sure that "x" is lower case? — the busybee
– the busybee, Commented Jun 21, 2020 at 20:16
You might like to print the read instruction to see what you got, for example like this: printf("\"%s\"\n", strg); — the busybee
– the busybee, Commented Jun 21, 2020 at 20:18
I tried printing the read line as using the statement you mentioned, it showed the inputted result but it was between quotation marks, does that make a difference? and has "x" is lower case when inputted — Mina Basem
– Mina Basem, Commented Jun 21, 2020 at 20:52

0___________ · Accepted Answer · 2020-06-21 17:15:49Z

1

The strg[3] is too short to accommodate the 2 chars string. It is an Undefined Behaviour.

As it is undefined it works in some environment and does not in another.

answered Jun 21, 2020 at 17:15

0___________

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1 Comment

Mina Basem Over a year ago

I changed the 3 to a 10 and still no difference.

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