Question

In C language

This program reads in a series of words. All words consist of only lower-case letters ('a' through 'z'). None of the words entered will be longer than 50 letters. The program reads until ctrl-d (end-of-file), and then prints out all the lower-case letters that were missing in the input or a statement indicating the input has all the letters. Two executions of the program are shown below.

Enter your input:
the quick brown fox jumps over the lazy old dog
Your input contains all the letters

Enter your input:
alabama crimson tide
Missing letters: f g h j k p q u v w x y z

Hints:

• Use an array of 26 elements to store the number of times you have seen the characters 'a' through 'z'. 'a' is actually an integer of value 97 (its ASCII value). If you subtract 'a' (or 97) from a lower-case letter, you will get a number in the range of 0 to 25.
• To test this program, it is a good idea to create a file (input1.txt for example) to contain all the input words. Then test the program with input redirection: ./a.out < input1.txt (or ./a.exe < datafile). Make sure the input file ends with a newline.

LAB

Answer 1

Please find the following c program to find whether all the alphabets are in the string entered by the user.

Note: I have added screen shots and comments as needed inline.

Program:

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

//number of alphabets available
#define MAX 26

int main()
{
int ch1=1, ch2, i =0;
int alph[MAX];
char buf, buf1;
int flag= 0, firstChar=1;

memset(alph, 0, sizeof(alph));
printf("Enter your input:\n");

//read the character and update the aplh array
while ((read(0, &buf, sizeof(buf))) != 0)
{
ch1=buf;
//if its lower case letter and its new letter
//update the array's respective index
if( ch1 >= 97 && ch1 <= 122)
{
   int value = ch1 - 'a';
   if(alph[value]==0)
   {
       alph[value]=1;
   }
}
buf='\0';
fflush(stdin);
}

//print the missing letters
printf("\n");
for(i=0; i<MAX; i++)
{
if(alph[i] == 0)
{
   if (flag == 0)
   {
       printf("Missing letters: ");
       flag = 1;
   }
     
   printf(" %c", 'a' + i);
}
}

//if all letter are present in the array, then print
//following message
if (flag == 0)
{
printf("Your input contains all the letters\n");
}
else
{
printf("\n");
}

return 0;
}

Output:

osboxes@osboxes:~/Chegg/C$ ./a.out
Enter your input:
asdf
Missing letters: b c e g h i j k l m n o p q r t u v w x y z
osboxes@osboxes:~/Chegg/C$ ./a.out <text
Enter your input:

Missing letters: e f g h i j k l m n o p q r s t u v w x y z
osboxes@osboxes:~/Chegg/C$ ./a.out
Enter your input:
the quick brown fox jumps over the lazy old dog
Your input contains all the letters
osboxes@osboxes:~/Chegg/C$

Screen Shot:

Text file containing the input: