Adding scanf and EOF to program - c

Question

#include <stdio.h>
#include <string.h>
int main()
{
char string[100];
int c = 0, count[26] = {0};
int accum = 0;
printf("Enter a string\n");
gets(string);
while ( string[c] != '\0' )
{
if ( string[c] >= 'a' && string[c] <= 'z' ){
count[string[c]-'a']++;
accum++;
}
else if (string[c] >= 'A' && string[c] <= 'Z'){
count[string[c]-'A']++;
accum++;
}
c++;
}
for ( c = 0 ; c < 26 ; c++ )
{
if( count[c] != 0 )
printf( "%c %f\n", c+'a', ((double)count[c])/accum);
}
return 0;
}
This should be an easy question, but I can't seem to get it to work. Right now, I have the print statement "Enter a string". I want to change it so that the user can keep inputting a string using scanf instead of printf until EOF is reached. Basically I want to remove the "Enter a string" statement and just have input a string until EOF and then have the letter frequency run once on all the strings inputted. How would I do that?

Answer 1

To do this using scanf() for input.
scanf() returns EOF when the EOF condition or IO error occurs.
// printf("Enter a string\n");
char ch;
while (scanf("%c", &ch) == 1) {
if ( ch >= 'a' && ch <= 'z' ){
count[ch-'a']++;
accum++;
}
...
}
Using int ch = fgetc(stdin) would make more sense.
"The fscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the function returns the
number of input items assigned, which can be fewer than provided for, or even zero, in
the event of an early matching failure." C11dr §7.21.6.2 16

Answer 2

Add your printf and gets statements inside the while loop
printf("Enter a string\n");
gets(string);
while ( string[c] != '\0' )
{
...//remaining code inside while loop
printf("Enter a string\n");
gets(string);
}
... //for loop code and return 0;

Answer 3

Here you go. I zeroed the variables for each loop. And I treated a blank entry (just press Enter) as EOF. But if you wanted the statistics for all the strings, don't zero the values at the start of the while loop
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
char string[100];
int c = 0, count[26] = {0};
int accum = 0;
do {
c = 0;
accum = 0;
memset (count, sizeof count, 0);
gets(string);
if (strlen (string) < 1)
break; // terminate
while ( string[c] != '\0' ) {
if ( string[c] >= 'a' && string[c] <= 'z' ) {
count[string[c]-'a']++;
accum++;
}
else if (string[c] >= 'A' && string[c] <= 'Z') {
count[string[c]-'A']++;
accum++;
}
c++;
}
for ( c = 0 ; c < 26 ; c++ ) {
if( count[c] != 0 )
printf( "%c %f\n", c+'a', ((double)count[c])/accum);
}
}
while (1);
return 0;
}