Codeblock

**s8884** · 02-16-2022

Hello,

in onlinegdb this program works, but in codeblock the output is not correct - any idea?
Thank you very much!
The output in codeblock is with weird characters.

Code:

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


int main()
{
    char name[32];
    char buffer[64];
    char last[]= "passed the challenge!\n";
    int ch, a;


    printf("What is your name? ");


    a=0;


    while ((ch = getchar()) != '\n')
          {
              name[a] = ch;
              a++;
              if(a==31)
                break;




          }
    strcpy(buffer,name);
    strcat(buffer," ");
    strcat(buffer,last);


    a=0;
    while(putchar(buffer[a++]))
          ;


    return(0);

**Salem** · 02-16-2022

Well your input loop fails to add a proper \0 string termination to the string you input.

At which point, it's a crap-shoot as to what happens next.

I guess you got unlucky on onlinegdb because it made you believe your faulty program was good.

**john.c** · 02-16-2022

Code:

while(putchar(buffer[a++]))
    ;

I don't think this is a good idea. If putchar fails for some reason and returns EOF it will loop forever since EOF is guaranteed to be negative and therefore "true". Also, the '\0' is sent to putchar, and I'm not sure what putchar is allowed to do in that situation. Is it specifically defined to do nothing on input of '\0'?

Perhaps it could be

Code:

while (buffer[a] && putchar(buffer[a++]) != EOF)
    ;

That's a little overkill for an EOF that's expected to be unlikely, so something like this is more usual, which still mitigates the infinite loop problem on EOF.

Code:

    while (buffer[a]) putchar(buffer[a++]);

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