100% prog to read only specific characters and discard others using scanf

/* prog to demonstrate variety of scanf where only permitted characters are read */
#include <stdio.h>
void main()
{
  char line[81];
  printf("\n enter some characters (upto81):");
 scanf("%[ abcdefgh]",line);// just prior to abcdefgh there is a white space
 printf("\n string in line =%s",line);
}

/*the idea is taken from NPTEL lectures of Prof. Anupam Basu  video: on Arrays & strings that follows the 'functions' video */

ఔట్పుట్ తెరమీద

keep on entering characters in a line:abc efa#1b

string in line =abc efa

గమనిక  ఒకసారి #వంటి invalid character ఇస్తే ఇక ఆ తర్వాత valid characters ఉన్నా అది తీసుకోలేదు

ఔట్పుట్ తెరమీద మరోసారి

keep on entering characters in a line:qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq
string in line =

గమనిక q అనేది valid character కాదు గనుక string in line= తర్వాత ఏమీ లేదు!

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