c - Strlen gives an incorrect output after fgets

Question

I read a string using fgets. It prints correctly but if i try to output the length using a strlen or a while until NULL it returns a bad value. Does fgets not end the string with NULL?

char word[256];
fgets(word, sizeof(word), stdin);
while(word[i])
    i++;
printf("%d",i);

For the string aba it outputs 40.

Answer 1

Function fgets also includes the new line character in the string. So function strlen counts this symbol.

From the C Standard

2 The fgets function reads at most one less than the number of characters specified by n from the stream pointed to by stream into the array pointed to by s. No additional characters are read after a new-line character (which is retained) or after end-of-file. A null character is written immediately after the last character read into the array.