passing uninitialized character array to function. Crashing - c

Question

The string lengths are not getting the correct lengths, so the rest of the program doesn't work. I am trying to read 62 chars per line then print a new line with another 62 chars.
Can anyone help me correctly pass the char arrays to the output function?
#include <stdio.h>
#include <string.h>
#define _CRT_SECURE_NO_DEPRECATE
void output(char *wbuf, char *lbuf, int lineLength);
void readFile(FILE *getty, char *wbuf, char *lbuf);
FILE *getty;
int main(void) {
char wbuf[1000] = {0}, lbuf[1000] = {0};
if (fopen_s(&getty,"getty.txt", "r") != 0 )
{
printf("Failed to open getty.txt for reading.");
} else {
readFile(getty, wbuf, lbuf);
}
fclose(getty);
return 0;
}
void readFile(FILE *getty, char *wbuf, char *lbuf)
{
static int lineLength = 62;
while (!feof(getty))
{
fscanf(getty, "%s", wbuf);
output(wbuf, lbuf, lineLength);
}
}
void output(char *wbuf, char *lbuf, int lineLength)
{
int wbufLength, lbufLength, i = 0;
wbufLength = strlen(wbuf);
lbufLength = strlen(lbuf);
//prints incorrect
printf("wbuflength %d lbuflength %d\n", wbufLength, lbufLength);
// lengths
if ( (wbufLength + lbufLength) <= lineLength)
{
strcat(lbuf,wbuf); //lbuf should be 0 but it starts at
} //274, wbuf not correct either
else
{
strcat(lbuf,"\n");
lineLength += 62;
strcat(lbuf, wbuf);
}
}

Answer 1

The problem is your loop condition:
while (!feof(getty)) { ... }
The EOF flag is not set until after an input operation fails.
In your case, the loop loops, then the fscanf operation fails because it's at the end of the file but you don't check for that inside the loop, and you then call output even though nothing was read from the file. Then the loop continues and then it notices that the file have reached EOF.