c - fgets 之后 Strlen 给出了错误的输出

Question

我使用 fgets 读取了一个字符串。它打印正确，但如果我尝试使用 strlen 或一段时间输出长度直到 NULL，它会返回一个错误值。 fgets 不是以 NULL 结束字符串吗？

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

对于字符串 aba，它输出 40。

Answer 1

函数fgets还包括字符串中的换行符。所以函数 strlen 计算这个符号。

来自 C 标准

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.