how to break from the function? - c

Question

I have the void function void isVaraRegistered that should check for existent numbers in the array that are introduced as varanummer in regVaror. If the introduced number already exists it should break from the regVaror function. I am not sure how to do it. How to set isVaraRegistered to true or false or any combination in fact. Please help!
//lager program lab
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define DEPOSIT 10
#define WORDLENGTH 30
#define MAX 10
struct varor{
int varunummer;
char namn[WORDLENGTH];
int lagersaldo;
};
typedef struct varor Vara;
Vara createVara(int varunummer, char namn[], int lagersaldo){
Vara v;
v.varunummer=varunummer;
strcpy(v.namn, namn);
v.lagersaldo=lagersaldo;
return v;
}
void isVaraRegistered(Vara reg[], int varunummer){
for(int n=0; n<MAX; n++){
if(reg[n].varunummer==varunummer) {
printf("\nError! Varunummer finns redan!\n\n");
}
break;
}
}
void regVaror( Vara reg[], int *pNrOfVaror){
char confirm;
char namn[WORDLENGTH],
tmp[WORDLENGTH];
int varunummer, lagersaldo;
printf("\nÄr du säkert att du vill registrera nya varor?\n1: Ja - (fortsätt)\n2: Nej - (gå tillbaka till menyn)\n");
scanf(" %c%*c", &confirm);// %*c för att inte skippa raden dvs skipppa ange varunummer
switch(confirm){
case '1':
do{
printf("Ange varunummer:");
gets(tmp);
varunummer=atoi(tmp);
isVaraRegistered(reg,varunummer);
printf("Ange namn:");
gets(namn);
printf("Ange lagersaldo:");
gets(tmp);
lagersaldo=atoi(tmp);
reg[*pNrOfVaror]=createVara(varunummer,namn,lagersaldo);
(*pNrOfVaror)++;
printf("\nRegristrera mer varor?\n1: Ja - (fortsätt)\n2: Nej - (gå tillbaka till menyn)\n");
scanf(" %c%*c", &confirm);
}while(confirm=='1');
case '2': break;
}
}
int main(){
int run=1;
Vara vRegister[MAX];
int nrOfVaror=0;
while(run){
char choice;
printf("\n\t\tMeny - Lager Program\n\n\
(1) Regristrera nya varor\n\b\b\b\b\
(2) Skriva ut alla varor\n\
(3) Söka efter varor\n\
(4) Ändra lagersaldot för varor\n\
(5) Sortera varor\n\
(6) Avregristrera varor\n\
(7) Avsluta programmet\n");
scanf(" %c%*c", &choice);
if(choice=='1') regVaror(vRegister, &nrOfVaror);
else if(choice=='7') run=0;
}
return 0;
}

Answer 1

A straight return will do it, but I tend to lean towards a more controlled exit in exceptional situations and let the function run through. Obviously there are scenarios where it's fine to have multiple returns but I try to keep it to a guard at the beginning and maybe a couple of special circumstances prior to finishing. But I wouldn't return from inside a loop. Just makes me feel dirty :)
So in your situation I would actually break as you are doing already which will return anyway... Your code is fine. But I'd lean towards this approach:
void isVaraRegistered(Vara reg[], int varunummer){
int found = 0;
for(int n=0; found == 0 && n<MAX; n++){
if(reg[n].varunummer==varunummer) {
printf("\nError! Varunummer finns redan!\n\n");//existing error msg
found++;
}
}
}
Note that this is just a personal coding style thing. Moving over to C# a few years ago thee was a push in our company to standardise and write a certain way and this sort of controlled execution of letting the full function run through was preferred.
--- Edit:
I was responding to the original code, you've updated since I started responding.
Incidentally, should should set int as your return type and return 1 or 0 indicating yes or no given the name of the function and return the found variable I introduced. Then where the function is called respond accordingly....and take out the printf as the function itself has one responsibility which is to answer the question 'isVaraRegistered?'. Any user I/O should be done outside this function.