Simple XOR encryption program not working as intended - c

Question

I'm writing a simple XOR encryption program in C.
It is supposed to read a text file line by line
and create a new encrypted file.
The problem is it is only encrypting the first line in the file, skipping the rest of file.
This is the code I've come up with.
From my analysis it should encrypt the file line by line.
But obviously I'm wrong somewhere, that's why it's misbehaving.
It would be really helpful if someone wiser could point out my mistake.
#include <stdio.h>
void encrypt(char *msg);
int main()
{
char line[100]; //all lines in file are shorter than 100 characters
FILE *in=fopen("msg.txt","r");
FILE *out=fopen("encrypted_msg.txt","a");
while(fscanf(in,"%99[^\n]",line)==1) // I included scanset to read new line in every iteration
{
encrypt(line);
}
fprintf(out,"%s\n",line);
return 0;
}
void encrypt(char *msg)
{
while(*msg)
{
*msg=*msg^31;
msg++;
}
}

Answer 1

It's simple. Just add:
char c = fgetc(in);
inside your while to read the endline \n.
Like this:
while(fscanf(in,"%99[^\n]",line)==1)
{
encrypt(line);
char c = fgetc(in);
}
You specified fscanf to read all symbols except the newline \n, so after the first while iteration there's a \n in input and on the second while iteration fscanf can read nothing cause you exclude \n from the permitted charset.

Answer 2

I think the answer from Edgar Rokyan works because fscanf does not remove the \n from the line so the next time it comes around the first char is a \n which is causes nothing to be read. My solution is to use fgets instead which reads the \n into the line buffer (if you don't want it there just check for it with an if statement and change the last char to a \0).
while(fgets(line, 99, in)) // I included scanset to read new line in every iteration
{
encrypt(line);
}
Or to get rid of the \n at the end of the line.
while(fgets(line, 99, in)) // I included scanset to read new line in every iteration
{
int len = strlen(line);
if(line[len - 1] == '\n')
line[len - 1] = '\0';
encrypt(line);
}