C，獲得（）與fgets（）

Question

char s1[100]; 
char s2[100]; 
gets(s1); 
fgets(s2,sizeof(s2),stdin); 
printf("%d,%d\n",strlen(s1),strlen(s2)); 

運行後，我輸入 「ABCD」 兩次， ，結果我得到的是：4,5 這是爲什麼？

Answer 1

從gets/fgets手冊頁：

The fgets() function reads at most one less than the number of characters 
specified by n from the given stream and stores them in the string s. 
Reading stops when a newline character is found, at end-of-file or error. 
The newline, if any, is retained. If any characters are read and there 
is no error, a `\0' character is appended to end the string. 

The gets() function is equivalent to fgets() with an infinite n and a 
stream of stdin, except that the newline character (if any) is not stored 
in the string. It is the caller's responsibility to ensure that the 
input line, if any, is sufficiently short to fit in the string. 

fgets保持換行符，這是字符數5，但gets沒有。 此外，養成一直使用fgets的習慣，因爲在使用gets時無法防止緩衝區溢出。

Answer 2

因爲fgets返回的字符串結尾爲'\n'而gets不是。

Answer 3

從gets() man page：

的gets()函數等效於fgets()具有無限n和的stdinstream，不同之處在於換行字符（如果有的話）不存儲在的字符串中。