Error in runtime

Code:

---

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

int main(void)
{
    char ar[20],*p;
    int a;
    gets(ar);
    if(a=atoi(ar))
        printf("%d",a);
    else
      {
            while(true)
            {
                p=strchr(ar,'s');
                if(*p=='\0')
                    break;
            }
            printf("why?");
      }
    return 0;
}

---

umm in that code i don't know why it produces a runtime error....i know that the problem
is somewhere in the memory but could someone help me so that it would not produce
a run-time error...thanks!!

Quote:

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if(*p=='\0')

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strchr returns a pointer to the char if it is found and NULL if it s not found.
hence, you want to check for -

Code:

---

if(p == NULL)

---

'\0' is the null terminating string of a char array and is different than a null pointer.
Cprogramming.com FAQ > NULL, 0, \0 and nul?

Also, you'll have to check for 's' too in case its found otherwise you'll enter an infinite loop.

Code:

---

if( *p == 's')
{
 // ..do something
  break;
}

---

Gets is evil. Never use it!

thanks spidey and elysia!!! i've forgot the difference between the '\0' and the NULL pointer... :D

umm guys i think 0 and '\0' is the same...correct me if i am wrong
here's the proof:

Code:

---

#include <stdio.h>

int main(void)
{
    char ar[5]="1234";
    short b;
    ar[0]=0;
    printf("%s\n",ar); 
    for(b=0;b<5;b++)
        ar[b]='s';
    printf("%s\n",ar);
    ar[0]='\0';
    printf("%s\n",ar);
    return 0;
}

---

Quote:

---

Originally Posted by sick

guys i think 0 and '\0' is the same

---

They have the same value and the same type. However, the point is that you should not use '\0' when you want a null pointer constant, because the contextual cue is that it has something to do with characters. You should use NULL, which is an implementation defined null pointer constant, or 0 if you wish to avoid the use of a macro.

thanks