read write binary into a string c - c

Question

So, I looked around the internet and a couple questions here and I couldn't find anything that could fix my problem here. I have an assignment for C programming, to write a program that allows user to enter words into a string, add more words, put all words in the string to a text file, delete all words in string, and when they exit it saves the words in a binary, which is loaded upon starting up the program again. I've gotten everything to work except where the binary is concerned.
I made two functions, one that loads the bin file when the program starts, one that saves the bin file when it ends. I don't know in which, or if in both, the problem starts. But basically I know it's not working right because I get garbage in my text file if I save it in a text file after the program loads the bin file into the string. I know for sure that the text file saver is working properly.
Thank you to anyone who takes the time to help me out, it's been an all-day process! lol
Here are the two snippets of my functions, everything else in my code seems to work so I don't want to blot up this post with the entire program, but if need be I'll put it up to solve this.
SIZE is a constant of 10000 to meet program specs of a 1000 words. But I couldn't get this to run even asking for only 10 elements or 1, just to clear that up
void loadBin(FILE *myBin, char *stringAll) {
myBin = fopen("myBin.bin", "rb");
if (myBin == NULL) {
saveBin(&myBin, stringAll);
}//if no bin file exists yet
fread(stringAll, sizeof(char), SIZE + 1, myBin);
fclose(myBin); }
/
void saveBin(FILE *myBin, char *stringAll) {
int stringLength = 0;
myBin = fopen("myBin.bin", "wb");
if (myBin == NULL) {
printf("Problem writing file!\n");
exit(-1);
stringLength = strlen(stringAll);
fwrite(&stringAll, sizeof(char), (stringLength + 1), myBin);
fclose(myBin); }

Answer 1

You are leaving bad values in your myBin FILE*, and passing the & (address) of a pointer.
Pass the filename, and you can (re) use the functions for other purposes, other files, et al.
char* filename = "myBin.bin";
Pass the filename, buffer pointer, and max size to read. You should consider using stat/fstat to discover file size
size_t loadBin(char *fn, char *stringAll, size_t size)
{
//since you never use myBin, keep this FILE* local
FILE* myBin=NULL;
if( NULL == (myBin = fopen(fn, "rb")) ) {
//create missing file
saveBin(fn, stringAll, 0);
}//if no bin file exists yet
size_t howmany = fread(stringAll, sizeof(char), size, myBin);
if( howmany < size ) printf("read fewer\n");
if(myBin) fclose(myBin);
return howmany;
}
Pass the file name, buffer pointer, and size to save
size_t saveBin(char *fn, char *stringAll, size_t size)
{
int stringLength = 0;
//again, why carry around FILE* pointer only used locally?
FILE* myBin=NULL;
if( NULL == (myBin = fopen("myBin.bin", "wb")) ) {
printf("Problem writing file!\n");
exit(-1);
}
//binary data may have embedded '\0' bytes, cannot use strlen,
//stringLength = strlen(stringAll);
size_t howmany = fwrite(stringAll, sizeof(char), size, myBin);
if( howmany < size ) printf("short write\n");
if(myBin) fclose(myBin);
return howmany;
}
Call these; you are not guaranteed to write & read the same sizes...
size_t buffer_size = SIZE;
char buffer[SIZE]; //fill this with interesting bytes
saveBin(filename, buffer, buffer_size);
size_t readcount = loadBin(filename, buffer, buffer_size);