Help with this. My error seems to be in trying to get the ? wildcard to function properly for the makefile. The ? wildcard works as intended, provided it is not the last character in the search. The line in bold is where the error pops up, I was wondering what part of this is actually causing this error to occur.

rgrep.c

#include

#define MAXSIZE 4096

char next_char(char *string) {

return *(string + sizeof(char));

}

char prev_char(char *string) {

return *(string - sizeof(char));

}

//Accepts char, not pointer

int is_operator(char pattern) {

switch(pattern) {

case '.' :

return 1;

case '\\' :

return 2;

case '+' :

return 3;

case '\?' :

return 4;

default :

return 0;

}

}

int plus_modified(char *pattern) {

if(next_char(pattern) == '+')

return 1;

return 0;

}

int question_modified(char *pattern) {

if(next_char(pattern) == '\?')

return 1;

return 0;

}

int escape_modified(char *pattern) {

if(prev_char(pattern) == '\\')

return 1;

return 0;

}

/**

* You can use this recommended helper function

* Returns true if partial_line matches pattern, starting from

* the first char of partial_line.

*/

int matches_leading(char *line, char *pattern) {

//Check direct match

if(*line == *pattern && !is_operator(*pattern)) {

return 1;

}

//Check wildcard match

if(*pattern == '.' && !escape_modified(pattern)) {

return 1;

}

//Check escaped operator match

if(*line == *pattern && is_operator(*pattern) && escape_modified(pattern)) {

return 1;

}

//Check escape character

if(*pattern == '\\')

return matches_leading(line, pattern + sizeof(char));

//Check for absent case of ? operator

if(question_modified(pattern))

return 1;

return 0;

}

/**

* You may assume that all strings are properly null terminated

* and will not overrun the buffer set by MAXSIZE

*

* Implementation of the rgrep matcher function

*/

int rgrep_matches(char *line, char *pattern) {

static int pattern_depth = 0;

//Base cases

if(*pattern == '\0') {

//Reset pattern for new line

if(*line == ' ') {

pattern -= pattern_depth * sizeof(char);

}

pattern_depth = 0;

return 1;

}

if(*line == '\0')

return 0;

//Reset pattern for new line

if(*line == ' ') {

pattern -= pattern_depth * sizeof(char);

pattern_depth -= pattern_depth;

return 0;

}

//Check for escape

if((*pattern == '\\') && is_operator(next_char(pattern))) {

pattern += sizeof(char);

pattern_depth++;

}

//Check for match

if(matches_leading(line, pattern)) {

//For + modifier

if(plus_modified(pattern)) {

int chars_before = 1;

if(*pattern == *(pattern + 2 * sizeof(char)))

chars_before = 2;

//Go to next nonmatching character

//Stops one before because there is a line increment at the end of rgrep_matches

while(*(line + chars_before * sizeof(char)) == *pattern && !(*pattern == '.' && !escape_modified(pattern)))

line += sizeof(char);

//Handle .+

if(*pattern == '.' && escape_modified(pattern)) {

char wildcard = *line;

while(*(line + chars_before * sizeof(char)) == wildcard)

line += sizeof(char);

}

if(*pattern == '.' && !escape_modified(pattern)) {

//while(*(line + chars_before * sizeof(char)) != *(pattern + 2 * sizeof(char)))

while(!matches_leading(line + chars_before * sizeof(char), pattern + 2 * sizeof(char))){

line += sizeof(char);

if((*line == '\0' || *line == ' ') && *(pattern + 2 * sizeof(char)) != '\0')

return 0;

}

}

//Compensate for the character that the operator took

pattern += sizeof(char);

pattern_depth++;

}

//For ? modifier

if(question_modified(pattern)) {

//

if (*pattern == '.' && !escape_modified(pattern) && escape_modified(pattern + 3 * sizeof(char)) && *line == *(pattern + 3 * sizeof(char)) && *(line + sizeof(char)) != *(pattern + 3 * sizeof(char))) {

pattern_depth += 4;

return rgrep_matches(line + sizeof(char), pattern + 4 * sizeof(char));

}

//

else if(*pattern == '.' && !escape_modified(pattern) && *line == *(pattern + 2 * sizeof(char))) {

pattern_depth += 2;

return rgrep_matches(line, pattern + 2 * sizeof(char));

}

//

else if(*pattern == '.' && !escape_modified(pattern) && *line != *(pattern + 2 * sizeof(char))) {

pattern_depth += 2;

return rgrep_matches(line + sizeof(char), pattern + 2 * sizeof(char));

}

//

else if(*line == *pattern && *line == *(pattern + 2 * sizeof(char))) {

pattern_depth += 2;

return rgrep_matches(line, pattern + 2 * sizeof(char));

}

//

else if(*line == *pattern && next_char(line) == *(pattern + 2 * sizeof(char))){}

//

else if(*line == *pattern && next_char(line) != *(pattern + 2 * sizeof(char)) && *line != *(pattern + 2 * sizeof(char)))

{}//return 0;

//

else if(*line != *pattern && *line != *(pattern + 2 * sizeof(char)))

return 0;

//

else if(*line == *pattern && *pattern == '.' && escape_modified(pattern)){}

//

else if(!(*pattern == '.' && !escape_modified(pattern)) || *line != *pattern)

line -= sizeof(char);

//Compensate for the character that the operator took

pattern += sizeof(char);

pattern_depth++;

}

pattern += sizeof(char);

pattern_depth++;

}

//Reset the pattern on partial match so that we only get contiguous matches

else if(pattern_depth != 0 && *(pattern - pattern_depth * sizeof(char)) != '\0') {

pattern -= pattern_depth * sizeof(char);

pattern_depth -= pattern_depth;

}

//if(*line != ' ')

line += sizeof(char);

//Recurse

return rgrep_matches(line, pattern);

}

int main(int argc, char **argv) {

if (argc != 2) {

fprintf(stderr, "Usage: %s ", argv[0]);

return 2;

}

/* we're not going to worry about long lines */

char buf[MAXSIZE];

while (!feof(stdin) && !ferror(stdin)) {

if (!fgets(buf, sizeof(buf), stdin)) {

break;

}

if (rgrep_matches(buf, argv[1])) {

fputs(buf, stdout);

fflush(stdout);

}

}

if (ferror(stdin)) {

perror(argv[0]);

return 1;

}

return 0;

}

MAKEFILE for the code

# Your program must compile with 'make'

# You must not change this file.

CC = gcc

FLAGS = -std=c99 -O0 -Wall -Werror -g -pedantic

rgrep:

$(CC) $(FLAGS) rgrep.c -o rgrep

clean:

rm -rf rgrep *.dSYM

check: clean rgrep

test "`echo "a b c" | ./rgrep 'a'`" = "a"

test "`echo "a " | ./rgrep 'a'`" = "a"

test "`echo "a" | ./rgrep '...'`" = ""

test "`echo "abc" | ./rgrep '.b.'`" = "abc"

test "`echo "h aaaaah" | ./rgrep 'a+h'`" = "aaaaah"

test "`echo "h aaaaahhhhh" | ./rgrep 'aa+hh+'`" = "aaaaahhhhh"

test "`echo "h aaaaahhhhh " | ./rgrep 'aa+hh+'`" = "aaaaahhhhh"

test "`echo "a" | ./rgrep 'a?a'`" = "a"

test "`echo "woot wot wat " | ./rgrep 'wo?t'`" = "wot"

test "`echo "CCCCCCC C+ C++" | ./rgrep '.\+\+'`" = "C++"

test "`echo "GG" | ./rgrep '.+'`" = "GG"

test "`echo "woooooo_CSE31.jpg" | ./rgrep 'w.+_...31\.jpg'`" = "woooooo_CSE31.jpg"

test "`echo "aab" | ./rgrep 'bb?'`" = "aab"

test "`echo "aaab" | ./rgrep 'a+b'`" = "aaab"

test "`echo "aaab" | ./rgrep 'a+ab'`" = "aaab"

@echo "Passed sanity check."