Question

Fill in the TODO parts of this skeleton to implement a miniature version of the GNU readline library. i.e. Store the characters in a malloc buffer as they come to you from stdio, and return the buffer.

skeleton code is:

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

char *readline(const char *prompt)
{
fputs(prompt ? prompt : "> ", stdout);
fflush(stdout);

int c;
// TODO: declare a char *

while ((c=fgetc(stdin)) != EOF)
{
// TODO: store c inside char * on the heap
// Use malloc and realloc as appropriate.
// Remember to zero terminate your buffers!
// Stop if you see '\n'
}

// TODO: return char*
}

int main()
{
char *buf = NULL;
while ((buf = readline(NULL)))
{
puts(buf);
free(buf);
}
return 0;
}

Answer 1

Given below is the code for the question. Please do rate the answer if it helped. Thank you.

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

char *readline(const char *prompt)
{
fputs(prompt ? prompt : "> ", stdout);
fflush(stdout);

int c;
char *str = NULL;
int n = 0;

while ((c=fgetc(stdin)) != EOF)
{
// store c inside char * on the heap
// Use malloc and realloc as appropriate.
if(str == NULL){
       str = malloc(sizeof(char) * 2);
   }
   else{
       str = realloc(str, sizeof(char) * (n+1));
   }
   if(c != '\n'){
       str[n] = c;
       n++;
   }
  
   // Remember to zero terminate your buffers!
   str[n] = '\0';
   // Stop if you see '\n'
   if(c == '\n')
       break;
}

   return str;
}

int main()
{
char *buf = NULL;
while ((buf = readline(NULL)))
{
puts(buf);
free(buf);
}
return 0;
}

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