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/* Splits up questions and answers in a \LaTeX file and saves each to separate files. Questions are prefixed by "\section*{". Answers are prefixed by "\subsection*{"
Copyright (C) 2021 Gentoo-libre Install
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>//basic I/O library
#include <stdlib.h>//library for malloc etc
#include <stdbool.h>//library for getting bools
#include <string.h>//We use this library just for strstr()
#define DEFAULT_SIZE 100//the default size of the buffer is 100 bytes (100 chars) to balance peformace and memory usage. Realloc is also increased by this much each time
int main(int argc, char *argv[])
{
if (!argv[1]){printf("No file given.\n"); return 1;}//return 1 if input isn't given
FILE *input = fopen(argv[1], "r");//file from where the question/answers are read
if (!input)
{
printf("%s %s\n", "Error opening input file:", argv[1]);
return 1;
}
FILE *questions = fopen("questions.tex", "a");//file where the questions are printed
if (!questions)
{
printf("Error opening output file questions.");
return 1;
}
FILE *answers = fopen("answers.tex", "a");//file where the answers are printed
if (!answers)
{
printf("Error opening output file answers");
return 1;
}
unsigned short size = DEFAULT_SIZE;//set size int to the DEFAULT_SIZE value. (Only an int because you can't increase the value of static symbolic values. {Muh memory wasted})
char *buffer = malloc(size*sizeof(char *));//malloc a 1D array of DEFAULT_SIZE length
if (!buffer){printf("Malloc failed!\n"); return 1;}//exit if malloc fails
char c;//buffer char
bool question_or_answer = false;//When the current line needs to be written to the questions file; bool is false. When the current line needs to be written to the answers file; bool is true;
unsigned short i = 0;//i is used to count how many chars have been written to the buffer.
char *temp;//a pointer to a char. strstr() wants this, so we use it.
c = fgetc(input);//read the first char in the file to c.
while(c != EOF)//exit if EOF is reached
{
if (c != '\n')//if read char isn't a newline, add it to the buffer.
{
if (i==size)//check for when the buffer is about to become larger than the memory allocated.
{
size+=DEFAULT_SIZE;//size = size + DEFAULT_SIZE, to add an extra 100 chars every realloc
buffer = realloc(buffer, size);//realloc the buffer larger to fix those extra chars.
if (!buffer){printf("Realloc failed!\n"); return 1;}//If out of memory, exit
}
buffer[i]=c; ++i; goto skip;//write char to buffer and skip ahead to next char reading
}
if (c == '\n')//If the current char is newline, analyse the now made buffer for a question or answer marking and write that to the correct file
{
buffer[i]=c;//Write newline to the buffer
temp = strstr(buffer, "\\section*");//If the current line is part of a question, "\section*" will be within it, and strstr will fine such
if (temp)//If temp isn't NULL, the string has been found
{
question_or_answer = false;//set the bool to question mode.
++i; buffer[i] = '\0';//add a NULL terminator to the buffer so it can be printed.
fprintf(questions,"%s", buffer);//output to the questions file with fprintf
i = 0;//reset the buffer counter ready for a new read into the buffer
goto skip;//skip ahead to reading the next char
}
temp = strstr(buffer, "\\subsection*");//if the current line has "\\subsection*" in it, strstr will find as such.
if (temp)//If temp isn't NULL, the string has been found
{
question_or_answer = true;//Set the bool to answer writing mode
++i; buffer[i] = '\0';//Add a NULL terminator to the buffer so it can be printed
fprintf(answers,"%s", buffer);//print the buffer to the answers file
i = 0;//reset the buffer counter
goto skip;//skip ahead to reading the next char
}
switch(question_or_answer)//If above fell through, then the line in the buffer is not a section or subsection, but is still under a question or an answer. The correct file should be written to.
{
case 0://if question_or_answer is false, the last defermined output was a question
++i; buffer[i] = '\0';//Add a NULL terminator so the buffer can be printed
fprintf(questions,"%s", buffer);//print the line to the questions file with fprintf
i = 0;//reset the buffer counter
break;//break so that the other case doesn't waste 1< CPU cycle checking for 1
case 1://If question_or_answer is true, the last determined output was an answer
++i; buffer[i] = '\0';///add a NULL terminator so that the line can be printed
fprintf(answers,"%s", buffer);//Use fprintf to write the line to the answers file
i = 0;//reset the buffer counter
//break; //yay, I saved a fraction of a CPU cycle by allowing a fall through instead of calling a break. (Or, I made it slower)
}
}
skip: c = fgetc(input);//read the next char before looping up to the start of processing. If there's no more chars to read, then the while loop will determine EOF and will exit
}
fclose(input);//close the input file
fclose(questions);//close the output file
fclose(answers);//close the output file
free(buffer);//free the malloce'd buffer
return 0;
}
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