Saving unwanted data to an error file - c

Question

Hi I currently have a piece of code that grabs names from a file and then saves it to another.
However I would now like to save any invalid information to a fixed error file and was wondering how I'd go about it
My code:
Struct:
struct Person{
char fName[16]; //string to store the persons first name
char lName[21]; //string to store the persons last name
};
Main
int main(){
int recordCount = 0; //used to keep track of the number of records currently in memory
struct Person *records;
records = malloc(sizeof(struct Person));
records = open(&recordCount, records);
records = addRecord(&recordCount, records);
save(recordCount, records);
return 0; //End the program and return 0 to the operating system
}
open(&recordCount, records) function:
struct Person* open(int *rCount, struct Person *records){
FILE *recordFile;
char fileName[30] = {'\0'};
int i = *rCount;
char test;
puts("Enter a filename to open :");
scanf("%s", fileName);
if((recordFile = fopen(fileName,"r"))==NULL){
printf("Couldn't open the file: %s\n",fileName);
exit(1);
}
else{
test = fscanf(recordFile,"%s %s", records[i].fName,records[i].lName);
while(test!= EOF){
i++;
records = realloc(records,(i+1)*sizeof(struct Person));
test = fscanf(recordFile,"%s %s", records[i].fName,records[i].lName);
}
fclose(recordFile); // close the file
}
*rCount = i;
return records; //add i (records read from the file) to rCount (the current record count)
}
addRecord(&recordCount, records) function
struct Person* addRecord(int* rCount, struct Person *records){
int valid = 0; //used to indicated valid input
int length = 0; //used to store the string lengths
int i = 0; //used in the for loops
char fNameTest[16]; //temporary storage of input to be checked before adding to records
char lNameTest[21]; //temporary storage of input to be checked before adding to records
//Checking the length of data input for fName
do{
length = strlen(fNameTest);
if(length < 16){
for(i=0;i<=length;i++)
records[*rCount].fName[i] = fNameTest[i]; //if correct insert the record at the index determined by rCount
valid=1;
}
else{
valid = 0;
}
}while(valid!=1);
//Checking the length of data input for lName
do{
length = strlen(lNameTest);
if(length < 21){
for(i=0;i<=length;i++)
records[*rCount].lName[i] = lNameTest[i]; //if correct insert the record at the index determined by rCount
valid=1;
(*rCount)++; //At this point ID,fName and lName have been stored so increment rCount
}
else{
valid = 0;
}
}while(valid!=1);
records = realloc(records,((*rCount)+1)*sizeof(struct Person));
return records; //return rCount as the new updated recordCount
}
save(recordCount, records) function
void save(int rCount, struct Person *records){
FILE *recordFile; //file handle
char fileName[30] = { '\0'}; //string to store the file name
int i;
puts("Enter a filename to save the records :"); //ask the user for the filename
scanf("%s", fileName); //store the filename: data input should be checked
//here in your program
//try and open the file for writing and react accordingly if there is a problem
if((recordFile = fopen(fileName,"w"))==NULL){
printf("Couldn't open the file: %s\n",fileName);
}
else{ //the file opened so print the records array of Person's to it
for(i=0;i<rCount;i++){
fprintf(recordFile,"%s %s\n",records[i].fName,records[i].lName);
}
fclose(recordFile); //close the file
printf("Records saved to file: %s\n",fileName);
}
}
I was thinking of removing the do-while loops in the addRecords function and replacing them with if statements. And then finally an if statement to check the value of valid. And then if valid=0 point to a function or save the errorfile directly there.
However I am unsure if this is the best way to go (or if my thought process would even work) and wondered if anyone could help.
Edit: Decided to add the type of data I'm dealing with incase anyone wants to create a .txt and run the program
Bob Jones
Franklin Davies
James Donut
EDIT Following the answer below I have updated my code (edited segments below)
EDITED saveFunction
void save(int rCount, struct Person *records){
FILE *recordFile; //file handle
char fileName[30] = { '\0'}; //string to store the file name
int i;
puts("Enter a filename to save the records :"); //ask the user for the filename
scanf("%s", fileName); //store the filename: data input should be checked
//here in your program
//try and open the file for writing and react accordingly if there is a problem
if((recordFile = fopen(fileName,"w"))==NULL){
printf("Couldn't open the file: %s\n",fileName);
}
else{ //the file opened so print the records array of Person's to it
char fileName[sizeof (struct Person) * 2]; // twice needed size
while (fgets(fileName, sizeof fileName, recordFile) != NULL) {
struct Person P;
int n; // Save index where scanning stopped
int cnt = sscanf(fileName,"%15s%21s %n", P.fName, P.lName, &n);
if (cnt != 2 || fileName[n]) {
errorLine(fileName);
// do not increment i;
} else {
// Good to keep
// realloc memory as needed here
records[i] = P;
i++;
}
}
errorLine function:
void errorLine(char *fileName)
{
FILE *errorFile;
//try and open the file for writing and react accordingly if there is a problem
if((errorFile = fopen("error.txt","w"))==NULL){
printf("Couldn't open the file:\n");
}
else{ //the file opened so print the records array of Person's to it
for(i=0;i<rCount;i++){
fprintf(errorFile,"%i %s %s\n",records[i].fName,records[i].lName);
}
fclose(errorFile); //close the file
printf("Records saved to file: %s\n",fileName);
}
}
No doubt I probably implemented the answer incorrectly and now get an error:
error: expected declaration or statement at end of input
Which is found on my last line of the program

Answer 1

Need to limit length of input before attempting to save in structure.
else {
char buffer[sizeof (struct Person) * 2]; // twice needed size
while (fgets(buffer, sizeof buffer, recordFile) != NULL) {
struct Person P;
int n; // Save index where scanning stopped
int cnt = sscanf(buffer,"%15s%21s %n", P.fName, P.lName, &n);
if (cnt != 2 || buffer[n] || MaybeAddtionalTests(&P)) {
SaveBadLine(buffer);
// do not increment i;
} else {
// Good to keep
// realloc memory as needed here
records[i] = P;
i++;
}
}
fclose(recordFile); // close the file