How can I get a string from input without including a newline using fgets?

Question

I'm trying to write an inputted string elsewhere and do not know how to do away with the new line that appears as part of this string that I acquire with stdin and fgets.

 char buffer[100];
 memset(buffer, 0, 100);
 fgets(buffer, 100, stdin);
 printf("buffer is: %s\n stop",buffer);

I tried to limit the amount of data that fgets gets as well as limiting how much of the data is written but the new line remains. How can I simply get the inputted string up to the last character written with nothing else?

@BLUEPIXY `scanf("%99[^\n]%*c", buffer)` will not read anything into `buffer` if the first `char` is `'\n'`. The `'\n'` remains in `stdin`. — chux - Reinstate Monica, Dec 15 '14 at 20:07
Do you want to read a line and leave the `'\n'` in the input stream, or do you want to read a line including the `'\n'` and then discard the `'\n'`? (This will affect the next input operation, which will or will not see the `'\n'` waiting for it.) — Keith Thompson, Dec 15 '14 at 20:13

score 5 · Answer 1 · answered Dec 15 '14 at 18:59

5

try

fgets(buffer, 100, stdin);
size_t ln = strlen(buffer)-1;
if (buffer[ln] == '\n')
    buffer[ln] = '\0';

answered Dec 15 '14 at 18:59

madz

1,803
18
45

score 5 · Answer 2 · edited May 23 '17 at 11:54

Simply look for the potential '\n'.

After calling fgets(), If '\n' exists, it will be the last char in the string (just before the '\0').

size_t len = strlen(buffer);
if (len > 0 && buffer[len-1] == '\n') {
  buffer[--len] = '\0';
}

Sample usage

char buffer[100];
// memset(buffer, 0, 100); not needed
if (fgets(buffer, sizeof buffer, stdin) == NULL) { // good to test fgets() result
  Handle_EOForIOerror();
}
size_t len = strlen(buffer);
if (len > 0 && buffer[len-1] == '\n') {
  buffer[--len] = '\0';
}
printf("buffer is: %s\n stop",buffer);

Notes:

buffer[strlen(buffer)-1] is dangerous in rare occasions when the first char in buffer is a '\0' (embedded null character).

scanf("%99[^\n]%*c", buffer); is a problem if the first char is '\n', nothing is read and '\n' remains in stdin.

strlen() is fast as compared to other methods: https://codereview.stackexchange.com/a/67756/29485

Or roll your own code like gets_sz

How can I get a string from input without including a newline using fgets?

2 Answers2

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