How to get a string input from stdin that has leading white space in C?

Question

Need a solution to get input string start with spaces?

I know a method to include space in input

scanf("%[^\n]s", s);

But its working only for space between words. I need a solution for string starts with spaces. And I also need the starting spaces in the variable

May I ask why the leading white space is required to be contained in the string? — RobertS supports Monica Cellio, Feb 17 '20 at 16:53
@RobertSsupportsMonicaCellio Its actually for the problem solving in online judge. — Aziz Ahmed, Feb 17 '20 at 16:55
@user3121023 ```scanf("%[^\n]", s);``` The starting space is ignored by this. :/ — Aziz Ahmed, Feb 17 '20 at 17:43
@AzizAhmed `scanf("%[^\n]", s);` does **not** ignore starting space. Instead, use of a prior `scanf("%[^\n]", s);` left the `'\n'` in `stdin` and `scanf("%[^\n]", s);` quit due to that `'\n'`. Save yourself grief. Do not use `scanf()` until you know why it is bad. — chux - Reinstate Monica, Feb 17 '20 at 23:19

score 3 · Accepted Answer · edited Feb 17 '20 at 20:18

3

To get a line of user input, use fgets().

#define S_MAX_LENGTH
char s[S_MAX_LENGTH + 2];
if (fgets(s, sizeof s, stdin)) {
  s[strcspn(s, "\n")] = '\0'; // Should code want to lop off a potential trailing \n
  ....

Do not use scanf("%[^\n]s", s); nor gets(s);. They suffer from buffer overflow and other issues.

edited Feb 17 '20 at 20:18

ad absurdum

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answered Feb 17 '20 at 20:00

chux - Reinstate Monica

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Furthermore, the trailing `s` in `"%[^\n]s"` is incorrect. – chqrlie Feb 17 '20 at 21:13

How to get a string input from stdin that has leading white space in C?

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