Writing to file and using if statments with loops - c

Question

I am creating a simple system for people to enter there basic details, have them printed on the screen and once confirmed writen to a text file, is the info is wrong the user enters edit ot be looped back to the beginning of the report and if another input is ented it asks the question again. Im a struggling to get the print to file to work and the two end loops.
#include <stdio.h>
#include <string.h>
int get_line(const char *prompt, char *dest, size_t size) {
printf("%s", prompt);
fflush(stdout);
if (fgets(dest, size, stdin) == NULL) {
dest[0] = '\0';
return 0;
}
dest[strcspn(dest, "\n")] = '\0'; // Lop off potential trailing '\n'
return 1;
}
int main(void)
{
char first_name[20], surname[20], street_no[10], street_name[40], postcode[10], contact_no[20], save_edit_qu[10];
int dd, mm, yy;
get_line(" Enter first name:\n", first_name, sizeof first_name);
get_line(" Enter surname:\n", surname, sizeof surname);
get_line(" Contact Number\n", contact_no, sizeof contact_no);
get_line(" Street Number\n", street_no, sizeof street_no);
get_line(" Street Name\n", street_name, sizeof street_name);
get_line(" Postcode\n", postcode, sizeof postcode);
printf(" First Name : %s\n", first_name);
printf(" Surname : %s\n", surname);
printf(" Contact No.: %s\n", contact_no);
printf(" Street No. : %s\n", street_no);
printf(" Stret Name : %s\n", street_name);
printf(" Postcode : %s\n", postcode);
get_line(" If the informations above is correct please enter SAVE/if you wish to change any informations please enter edit", save_edit_qu, sizeof save_edit_qu);
if (save_edit_qu[0] == 'SAVE' || save_edit_qu[0] == 'save') {
//write info to file
}
if (save_edit_qu[0] == 'EDIT' || save_edit_qu[0] == 'edit') {
//loop back to beginning of report
}
else if ()//loop to beginning of SAVE/EDIT QU
return 0;
}

Answer 1

use strcmp() and use double quotes "" for string !
if (strcmp(save_edit_qu,"SAVE") == 0 || strcmp(save_edit_qu,"save") == 0) {
or test only first character using single quotes like this
if (save_edit_qu[0] == 'S' || save_edit_qu[0] == 's') {

Answer 2

So, there are a couple of things wrong about your program. I'll try to cover them all here before I show you the changes.
Your string comparison is simple nonsensical: save_edit_qu[0] == 'SAVE' simply compares the first character/byte of save_edit_qu to 'SAVE', which itself isn't a proper string literal. You've got to enclose string literals in double quotes in C. And even if you did do that here, it doesn't make sense to compare a character to a string. What you should do is use strcmp from string.h to do the comparison for you. I've placed that inside my fixed version of your program. The format is: strcmp(a,b) == 0 if string a is equal to string b.
You're giving users the ability to edit all their input data. Therefore, you should be placing your data collection in a loop. This allows you to constantly re-collect the data as long as the user isn't done.
do {
// collect data.
} while (!done);
Finally, you're having users perform an action within the data collection loop so that they can choose what they'd like to do with the data. They can either edit, or save. There's also the case they enter neither. In this case, they'll be prompted again. This warrants another control loop inside.
do {
// collect data
do {
// save or edit
} while (!validChoice);
} while (!done);
With this said, here is the working program. I have not implemented the writing-to-file portion for you though. I think you can give that a shot yourself!
#include <stdio.h>
#include <string.h>
int get_line(const char *prompt, char *dest, size_t size) {
printf("%s", prompt);
fflush(stdout);
if (fgets(dest, size, stdin) == NULL) {
dest[0] = '\0';
return 0;
}
dest[strcspn(dest, "\n")] = '\0'; // Lop off potential trailing '\n'
return 1;
}
int main(void)
{
char first_name[20], surname[20], street_no[10], street_name[40], postcode[10], contact_no[20], save_edit_qu[10];
int dd, mm, yy, done = 0;
// Data collection loop: Runs as long as the user opts to edit the data.
do {
// Fetch data.
get_line(" Enter first name:\n", first_name, sizeof first_name);
get_line(" Enter surname:\n", surname, sizeof surname);
get_line(" Contact Number\n", contact_no, sizeof contact_no);
get_line(" Street Number\n", street_no, sizeof street_no);
get_line(" Street Name\n", street_name, sizeof street_name);
get_line(" Postcode\n", postcode, sizeof postcode);
printf(" First Name : %s\n", first_name);
printf(" Surname : %s\n", surname);
printf(" Contact No.: %s\n", contact_no);
printf(" Street No. : %s\n", street_no);
printf(" Stret Name : %s\n", street_name);
printf(" Postcode : %s\n", postcode);
// Action loop: Runs as long as no valid input is given.
do {
get_line(" If the informations above is correct please enter SAVE/if you wish to change any informations please enter edit\n", save_edit_qu, sizeof save_edit_qu);
// Option to quit.
if (strcmp(save_edit_qu, "SAVE") == 0 || strcmp(save_edit_qu, "save") == 0) {
fprintf(stdout, "Writing data to file...\n");
// write data here.
// Set done flag, and exit action loop.
done = 1;
break;
}
// Option to edit.
if (strcmp(save_edit_qu, "EDIT") == 0 || strcmp(save_edit_qu, "edit") == 0 ) {
//loop back to beginning of report
break;
}
// Otherwise ask prompt again ^.
} while (1);
} while (!done);
return 0;
}