When I do practice on K&R,I found a very interesting question:
code as follows:
include <stdio.h>
main()
{
int c;
int bn;
bn=0;
while((c=getchar())!=EOF)
{
if(c==' ')
bn++;
}
printf("blanks counter:%d\n",bn);
}
code function is number of statistical blankspaces
I enter all the words at once ,no use backspace key,it is done.
$ ./a.out
I have a dream
blanks counter:3
however,if I use backspace key,what happen may be in input process?
I speculate when a blankspace key is pressed ,getchar() function should get this event,and then perform bn++ ,so even if I later press a backspace key to delete this blankspace ,the value of bn variable is not change. but the result of practice is different of my speculate, the programe of practice as follows:
the first step:input first blankspace
the second step:use backspace key delete thie blankspace
the third step:finish the remaining input of characters
why result is 3 not 4?why value of bn variable would be changed by pressed backspace key?
please give me some ideas,thanks!
