C/ctype.h/isalpha
int isalpha(int ch)
//Declaration: int isalpha(int ch);
//Return: returns nonzero if ch is a letter or zero if not.
#include <ctype.h>
#include <stdio.h>
int main(void)
{
char ch;
for(;;) {
ch = getchar();
if(ch == ".") {
break;
}
if(isalpha(ch)) {
printf("%c is a letter\n", ch);
}
}
return 0;
}
/*
a
a is a letter
a
a is a letter
d
d is a letter
.
*/