#include <stdio.h>
#include <ctype.h>

int isvowel(int c);
int main (void)

{
int c;
printf("INPUT YOUR TEXT: \n\n");
while((c = getchar()) != EOF) 
{
if(isvowel(c))
putchar(c);
}
return 0;
}
int isvowel(int c)
{
if (c=='a'||c=='e'||c=='i'||c=='o'||c=='u'||c=='A'||c=='E'||c=='I'||c=='O'||c=='U')
return 0;
return 1;
}

#include <stdio.h>                            /* srteasy  srt1.c */
/* #include <ctype.h>  <- you do not need that */

int isvowel(int c);  /* very good */

int main (void)
{
  int c = 0;
  
  /* use loop inside loop to separate the input part from the output part */
  while(c != 0x1b)    /* 0x1b is ascii code for escape key */
  {
    printf("\nINPUT YOUR TEXT:      (ESC to exit) \n"); 
    /* while((c = getchar()) != EOF) */
    while((c = getchar()) != '\n' && c != 0x1b)  /* get out of this loop on either */
    {
      if(isvowel(c))
        putchar(c); /* try writing to a char array here instead of the putchar */
    }
    /* when input is done, you print your fancy message including the string */
    putchar(0x0a);
    /* do you want another getchar() here for "anykey"  ? */
  }
  return 0;
}