Reading a string from stdin in c

Question

I wrote a simple program to read a string.

void main()
{
    char *str; /*didn't allocate memory*/
    scanf(" %s",str);
    printf("%s",str);
}

But it is causing a segmentation fault. Whereas the next one isn't.

void main()
{
    char *str;
    scanf(" %c",str);
    printf("%c\n",str);
}

Would someone mind to clarify how actually this works?

Answer 1

You string isn't allocated. which mean you are writing somewhere you didn't ask for.

however what you can do is:

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

int main(int argc, char *argv[])

{
  char c;
  while (scanf("%c",&c) && c != '\n')
    printf("%c",c);
  printf("\n");

  return 0;
}

It will read every characters you send in input until you press return.