Mergesort is of the devil
So I'm having trouble getting my mergesort functions to work. The first function mergesort works fine, but then when the program calls merge it crashes. Heres mergesort:
Mergesort function
Code:
void mergesort(struct comic **comics, int len)
{
struct comic *left;
struct comic *right;
int ct;
printf("test1");
if(len <= 1)
{
return;
}
else{
left = (struct comic*)calloc(len/2, sizeof(struct comic));
for(ct = 0; ct < len/2; ct++)
{
left[ct] = *comics[ct];
}
mergesort(&left, len/2);
right = (struct comic*)calloc(len - len/2, sizeof(struct comic));
for(ct = len/2; ct<len; ct++)
{
(right)[ct - len/2] = (*comics)[ct];
}
mergesort(&right, len - len/2);
printf("test1");
merge(&comics, &left, len/2, &right, len-len/2);
free(left);
free(right);
}//end else
}//End mergesort
So when it gets done with the first few operations and hits the call for merge the program jumps to the merge function:
Merge function
Code:
void merge(struct comic ***comicsc, struct comic **leftc, int leftlen, struct comic **rightc, int rightlen)
{
int comicsnum = 0;
int leftnum = 0;
int rightnum = 0;
//int righttst, lefttst;
printf("test1");
while(leftnum < leftlen && rightnum < rightlen)
{
if(leftc[leftnum]->issuenum <= rightc[rightnum]->issuenum)
{
**comicsc[comicsnum] = *leftc[leftnum];
comicsnum++;
leftnum++;
}
else
{
**comicsc[comicsnum] = *rightc[rightnum];
comicsnum++;
rightnum++;
}
}
printf("test");
//RIGHT WHEN IT GETS TO THE FOLLOWING LOOPS MY PROGRAM CRASHES
//I KNOW THIS BECAUSE IT STILL PRINTS THE PRINTF FUNCTION
//DIRECTLY ABOVE THIS
if(rightnum >= rightlen)
{
while(leftnum < leftlen)
{
**comicsc[comicsnum] = *leftc[leftnum];
comicsnum++;
leftnum++;
}
}
else
{
while(rightnum < rightlen)
{
printf("test1");
**comicsc[comicsnum] = *rightc[rightnum];
comicsnum++;
rightnum++;
}
}
//printf("test1");
}//End merge
Does anyone see whats happening in those loops in the merge function that could be causing my program to crash?
Here's how I'm declaring everything and then calling it, its the entire main function of my program.
Code:
main()
{
char filename[50], title[100], issue[100];
char *p;
char uscore = '_';
char blank = ' ';
int issuenum, numcomics, count = 0, cnt = 0, past = 0, pcnt = 0, tempcnt = 0;
struct comic *thecomics;
struct comic *temp;
FILE *f1;
printf("--------------------------------------------------------------------------------------");
printf("Welcome to the comic book sorter!\n");
printf("Please enter in the name of the file containing the comic books: ");
//fflush();
fgets(filename, sizeof(filename), stdin);
//Removes the \n that ENTER adds into the filename input
if((p = strchr(filename, '\n')) != NULL)
{
*p = '\0';
}
//Opens the file
f1 = fopen(filename, "r");
//fflush();
if(f1 != NULL)
{
fscanf(f1, "%d", &numcomics);
system("pause");
thecomics = (struct comic*)calloc(numcomics, sizeof(struct comic));
temp = (struct comic*)calloc(numcomics, sizeof(struct comic));
do
{
fscanf(f1, "%s %d %s", title, &issuenum, issue);
cnt = 0;
//Checks for the _ in the string and replaces it with a "space"
do
{
if(title[cnt] == uscore)
{
title[cnt] = blank;
}
cnt++;
}while(cnt < 100);
//Checks for the _ in the string and replaces it with a "space"
cnt = 0;
do
{
if(issue[cnt] == uscore)
{
issue[cnt] = blank;
}
cnt++;
}while(cnt < 100);
strcpy(thecomics[count].title, title);
strcpy(thecomics[count].issue, issue);
thecomics[count].issuenum = issuenum;
count++;
}while(count < numcomics);
//Sorts by title and then mergesorts by comic number and prints
count = 0;
do
{
//Tests to see if the title has already been run
pcnt = count - 1;
while(pcnt >= 0)
{
if(strcmp(thecomics[count].title, thecomics[pcnt].title) == 0)
{
past = 1;
}
pcnt--;
}
if(past != 1)
{
tempcnt = 1;
cnt = count +1;
do
{
if(strcmp(thecomics[count].title, thecomics[cnt].title) == 0)
{
temp[0] = thecomics[count];
temp[tempcnt] = thecomics[cnt];
tempcnt++;
}
cnt++;
}while(cnt < numcomics);
mergesort(&temp, tempcnt);
cnt = 0;
printf("%s\n", temp[0].title);
while(cnt <= tempcnt)
{
printf("\t%d. %s\n", temp[cnt].issuenum, temp[cnt].issue);
cnt++;
}
}//End IF
count++;
}while(count < numcomics);
system("pause");
}//Close if
else
{
printf("There is nothing in the file or it doesn't exist!\n");
}//Close Else
system("pause");
}//Close main
