C Problems with fscanf - c

Question

Thanks for all the answers, after the corrections the code did not work for a stupid error ... I opened both files with the same file pointer "database" ...
I've read dozens of questions like this but I can't get out of it, I'm going crazy.
The exercise that I have to do asks me to organize the items of a list in a file .txt that has elements of the type: Name Surname Age Wage, in alphabetical order according to the surname.
I have already created a function to insert the elements into the file and it works well.
I then went to the function to organize them but the process stops after the fscanf, and putting some test printf I saw that no values are assigned to the strings or that are assigned absurd numbers.
Please help ... thanks.
This is the code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAX 64
#define MAXFILE 100
void insert();
int fullcheck();
void sort();
typedef struct {
char name[MAX];
char surname[MAX];
int age;
double wage;
} data;
int main() {
insert();
return EXIT_SUCCESS;
}
void insert() {
char c;
int i;
data tmp;
FILE* database;
if ((fullcheck())>MAXFILE-1)
printf("Errore: database pieno.\n");
else {
database=fopen("database.txt", "a");
printf("Nome: ");
fgets(tmp.name, MAX, stdin);
tmp.name[strlen(tmp.name)-1]='\0';
printf("Cognome: ");
fgets(tmp.surname, MAX, stdin);
tmp.surname[strlen(tmp.surname)-1]='\0';
for (i=0; i<strlen(tmp.surname); i++) {
if (tmp.surname[i]==' ')
tmp.surname[i]='#';
}
printf("Eta': ");
scanf("%d", &tmp.age);
printf("Salario: ");
scanf("%lf", &tmp.wage);
while((c=getchar())!='\n');
fprintf(database, "%s %s %d %.0lf \n", tmp.name, tmp.surname, tmp.age, tmp.wage);
fflush(database); fclose(database);
if ((fullcheck())>1)
sort();
}
}
int fullcheck() {
char c;
int r=0;
FILE* database;
if ((database=fopen("database.txt", "r"))==NULL) {
return 0;
}
else {
while((c=getc(database))!=EOF) {
if(c=='\n')
r++;
}
return r;
}
}
void sort() {
char tmpstr[MAX];
int len=fullcheck(), i, a, b;
data tmp[len];
FILE* database;
FILE* sorted;
database=fopen("database.txt", "r");
database=fopen("sorted.txt", "w");
for (i=0; i<=len; i++) {
fscanf(database, "%s %s %d %lf \n", &tmp[i].name, &tmp[i].surname, &tmp[i].age, &tmp[i].wage);
}
for (a=0 ; a<(len-1); a++) {
for (b=0; b<(len-1); b++) {
if ((tolower(tmp[b].surname[0]))>(tolower(tmp[b+1].surname[0]))) {
strcpy(tmpstr, tmp[b].surname);
strcpy(tmp[b].surname, tmp[b+1].surname);
strcpy(tmp[b+1].surname, tmpstr);
}
}
}
for (a=0; a<(len-1); a++) {
fprintf(sorted, "%s %s %d %.0lf \n", tmp[a].name, tmp[a].surname, tmp[a].age, tmp[a].wage);
}
fflush(database); fclose(database); remove("database.txt");
fflush(sorted); fclose(sorted); rename("sorted.txt", "database.txt");
}

Answer 1

Off by 1
Code attempts to read into len+1 elements of tmp[].
data tmp[len];
for (i=0; i<=len; i++) { // too many
fscanf(database, "%s %s %d %lf \n", &tmp[i].name, &tmp[i].surname, &tmp[i].age, &tmp[i].wage);
}
I saw that no values are assigned to the strings (OP)
Better code would use width limits and test fscanf() result before using the data scanned.
// v---- < not <=
for (i=0; i<len; i++) {
if (fscanf(database, "%63s %63s %d %lf",
&tmp[i].name, &tmp[i].surname, &tmp[i].age, &tmp[i].wage) != 4) {
// ^^^^ test!
break;
}
Even better code would read a line with fgets() into a stirng and then attempt to parse the string.
Off by 2
Code's attempt to find number of lines can be short by 1 if the last line does not end with a '\n'.
Alternative
size_t fullcheck(void) {
FILE* database = fopen("database.txt", "r");
if (database == NULL) {
return 0;
}
int previous = '\n';
int c;
size_t r=0;
while((c=getc(database))!=EOF) {
if (previous == '\n') r++;
previous = c;
}
fclose(database);
return r;
}
Missing fclose()
fullcheck() doesn't close the file after opening it.
int
Use an int to distinguish the typically 257 different returns values of fgetc(). Note when char` is unsinged, OP's code is an infinite loop.
More woes
The loop to print the sorted list is off-by-one, too short. And the sorting itself only looks at the first letter of each name, should use strcmp.
#user3386109
Maybe more?

Answer 2

Make sure to close the file here, before every return:
int fullcheck() {
char c;
int r=0;
FILE* database;
if ((database=fopen("database.txt", "r"))==NULL) {
fclose(database);
return 0;
}
else {
while((c=getc(database))!=EOF) {
if(c=='\n')
r++;
}
fclose(database);
return r;
}
}
And also a little bit fixing in the loop_counters here:
void sort() {
char tmpstr[MAX];
int len=fullcheck(), i, a, b;
data tmp[len];
FILE* database;
FILE* sorted;
database=fopen("database.txt", "r");
sorted=fopen("sorted.txt", "w+");
for (i=0; i<len; i++) {
fscanf(database, "%s %s %d %lf \n", &tmp[i].name, &tmp[i].surname, &tmp[i].age, &tmp[i].wage);
printf("%s", tmp[b+1].surname);
system("pause");
}
for (a=0 ; a<(len); a++) {
for (b=0; b<(len); b++) {
if ((tolower(tmp[b].surname[0]))>(tolower(tmp[b+1].surname[0]))) {
strcpy(tmpstr, tmp[b].surname);
strcpy(tmp[b].surname, tmp[b+1].surname);
strcpy(tmp[b+1].surname, tmpstr);
printf("%s", tmp[b+1].surname);
system("pause");
}
}
}
for (a=0; a<(len); a++) {
fprintf(sorted, "%s %s %d %.0lf \n", tmp[a].name, tmp[a].surname, tmp[a].age, tmp[a].wage);
}
fclose(sorted);
fclose(database);
}