Can I read multiple lines from keyboard with fgets?

Question

I am trying to read a few lines from stdin (my keyboard) in C, and I wasn't able to do this.

My input it looks like this:

3 first line second line third line

There's my code:

char input[2], s[200]; if (fgets(input, 2, stdin) != NULL) { printf("%d\n", input[0]); for (int i = 1; i <= input[0] - '0'; i++) { if (fgets(s, 20, stdin) != NULL) printf("%d\n", s[1]); } }

It seems that this function, "fgets" is reading even my new line char, coded with 10 in ASCII. BTW, I am running my code in linux terminal.

That's correct, fget() reads the newline too (if there is room). That way, you know a complete line was read, not that the buffer was full. The program behaviour is undefined though, because fgets(s, 20, stdin) needs a buffer of size 20, not the 2 available in s[2]. — Weather Vane
– Weather Vane, Commented Dec 3, 2020 at 11:41

Krishna Kanth Yenumula · Accepted Answer · 2020-12-03 12:37:20Z

I am trying to read a few lines from stdin (my keyboard) in C, and I wasn't able to do this.

Reasons:

printf("%d\n", input[0]); This statement prints an extra \n, which is read by fgets during first iteration. So, s will store \n in the first iteration. Use getchar() to read that extra \n.
fgets(s, 20, stdin) , You are reading 20 bytes, but the input string (second one) occupies more than 20 bytes. Increase it.
printf("%d\n", s[1]); change to printf("%s\n", s);

The code is :

#include <stdio.h> #include <string.h> int main() { char input[2], s[200]; if (fgets(input, 2, stdin) != NULL) { printf("%d\n", (input[0]- '0')); getchar(); // to read that extra `\n` for (int i = 1; i <= (input[0] - '0'); i++) { if (fgets(s, 50, stdin) != NULL) // increase from 20 to 50 printf("%s\n", s); // printing string } } return 0; }

The output is :

3 3 this is first line this is first line this is the second line this is the second line this is the third line this is the third line

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