i have written this code and but it's not working properly

Question

I am writing a code that accepts a string of length as much a user want and displays it.so this is what I have written

#include<stdio.h>
#include<stdlib.h>
void main()
{
  char *a;
  int i,n;
  a=(char*)calloc(1,sizeof(char));
  printf("enter the string\t");
  for(i=0;a[i]!=0;i++)
  {
        scanf("%[^0]c",&a[i]);
        n=2+i;
        a=(char*)realloc(a,(n)*sizeof(char));
  }
  for(i=0;a[i]!=0;i++)
  {
        printf("%c",a[i]);
  }
  free(a);
  a=NULL;
}

but it's not entering into the loop and accepts any input. can you tell me what's going wrong? THANKS

Why are you printing character by character instead of putting this into a NULL-terminated string buffer and just feeding that to `printf` directly? While `free(a)` is understandable, setting `a` to `NULL` is really pointless. — tadman, Dec 19 '17 at 18:45
Normally you'd tackle this problem by allocating an optimistically large buffer and if the user exceeds that size, reallocate with double the size. This avoids relentless reallocation. — tadman, Dec 19 '17 at 18:46
Welcome to Stack Overflow! [Please see this discussion on why not to cast the return value of malloc() and family in C..](https://stackoverflow.com/q/605845/2173917) — Sourav Ghosh, Dec 19 '17 at 18:46
`scanf("%[^0]c",&a[i])` is not a valid format. I suggest you use `fgets` and reallocate in steps of say 100 bytes, and repeat until the `'\n'` newline is detected at the end of the input string. Note that `'\0'` does not terminate input strings, but only C strings. — Weather Vane, Dec 19 '17 at 18:53
Please don't edit your question from errors pointed out. Rolled back. — Weather Vane, Dec 19 '17 at 19:02
@WeatherVane `scanf("%[^0]c",&a[i])` is a valid format, yet certainly not what OP wants. — chux - Reinstate Monica, Dec 19 '17 at 19:46

score 1 · Accepted Answer · answered Dec 19 '17 at 18:47

1

You are not entering the loop because you allocated a with calloc, so a[0] is 0. It will fail the initial a[i]!=0 test of both of your for loops.

answered Dec 19 '17 at 18:47

Andrew Cottrell

3,312
3
26
41

but malloc() is also not solving the problem – Ashish Dogra Dec 19 '17 at 18:50
for strings of small length, it's working correctly but as the length grows it's stops working – Ashish Dogra Dec 19 '17 at 18:53
That's a separate problem. I explained why you weren't entering the loops. If you need more help please edit and update your question. – Andrew Cottrell Dec 19 '17 at 18:57

i have written this code and but it's not working properly

1 Answers1