Why are my pointer assignments causing program to crash - c

Question

I have written the code below as a small program to test out before writing a larger program based on the same basic principle. I had it working yesterday, but it's getting hung up this morning, and I can't figure out why.
The code is getting hung up at: new_rec->next = head;
Please have a look at the code below, and thanks for your help.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
FILE *fptr;
struct list {
char string[256];
char *ptr;
struct list *next;
};
unsigned int breakRemove(char string1[]);
int main(void)
{
if ((fptr = fopen("C:\\Users\\mgreene\\Documents\\EmailTemplates\\TestList.txt", "w")) == NULL)
{
fprintf(stderr, "Error opening file.");
exit(1);
}
int i, j, k, count=0;
char ans[256];
char *pAns;
pAns = ans;
struct list *ptr = NULL;
do
{
puts("\nEnter some text: ");
fgets(ans, 256, stdin);
breakRemove(ans);
if (pAns != '\0');
{
count++;
printf("\n%d. You typed:\"%s\"", count, pAns); //test for correct pAns pointer assignment
}
struct list list1;
struct list *head = NULL;
struct list *new_rec = NULL;
struct list *curr_rec = NULL;
struct list *next_rec = NULL;
new_rec = (struct list*)malloc(sizeof(struct list));
if (!new_rec)
{
puts("\nMemory Allocation Error");
exit(1);
}
puts("\nFirst Memory Allocation Successful."); //acknowledge successful memory allocation
ptr = pAns;
printf("\nptr = %s", ptr); //test for pointer assignment
printf("\npAns = %s", pAns); //test for pointer assignment
head = ptr;
printf("\nhead = %s", head);// test for pointer assignment
printf("\nProblem is new_rec->next=head."); //test to isolate problem.
new_rec->next = head;
printf("\nnew_rec->next = ", new_rec->next);
head = new_rec;
curr_rec = head;
while (curr_rec->next != NULL)
{
curr_rec = curr_rec->next;
}
puts("\nList Pointer Memory Allocation Successful.");
curr_rec->next = new_rec;
new_rec->next = NULL;
strcpy(new_rec->string, ans);
printf("\n%s", curr_rec->string);
if (list1.string != '\0')
{
fprintf(fptr, "\n%d. %s", count, curr_rec->string);
}
}while (*pAns != '\0');
}
unsigned int breakRemove(char string1[]) //Function for removing line breaks from fgets.
{
unsigned int lenString;
lenString = strlen(string1);
if (string1[lenString-1]=='\n')
{
string1[lenString-1]='\0';
}
return (unsigned char)string1;
}

Answer 1

Enable the warnings in your compiler. I got:
../main.c:53:9: warning: assignment from incompatible pointer type [enabled by default]
../main.c:54:5: warning: format ‘%s’ expects argument of type ‘char *’, but argument 2 has type ‘struct list *’ [-Wformat]
../main.c:57:5: warning: format ‘%s’ expects argument of type ‘char *’, but argument 2 has type ‘struct list *’ [-Wformat]
../main.c:62:5: warning: too many arguments for format [-Wformat-extra-args]
../main.c:44:18: warning: unused variable ‘next_rec’ [-Wunused-variable]
../main.c:23:13: warning: unused variable ‘k’ [-Wunused-variable]
../main.c:23:10: warning: unused variable ‘j’ [-Wunused-variable]
../main.c:23:7: warning: unused variable ‘i’ [-Wunused-variable]
../main.c: In function ‘breakRemove’:
../main.c:93:10: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
Fix them for a good start. :)
For example, the first warning is coming from
ptr = pAns;
and then this will be head. That's why your program crashes (one of the reasons probably).
You have
char *pAns;
struct list *ptr = NULL;
and then you assign the one to the other. This doesn't make sense. You should try/study harder, since the errors are many for an answer to fix them.
Another example is here:
if (pAns != '\0')
; <-- suspicious semicolon, remove it
{
count++;
printf("\n%d. You typed:\"%s\"", count, pAns); //test for correct pAns pointer assignment
}
To turn the warnings on in code blocks, you could do this:
"check the option "Enable all compiler warnings" in the settings=>configure plugins=>compiler"
or do this:
that I found here.