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i want, if the name and surname is found in the array, i want to return that the patient is found, otherwise he is not found.Code:bool check_if(informationT a[],int size){int i;
char sur[20],name[15];
printf("Give patient's last name \n");
gets(sur);
printf("Give patient's first name \n");
gets(name);
for (i=0; i<size; i++){
if ((sur == a[i].epwnymo) && (name == a[i].onoma))
return true;
else
return false;
}
}
i have tried break; too, but nothing changes.
All kind of help is welcome
Thanks
I suspect the compiler isn't sure whether either return statement gets triggered. If size is 0 for instance, it won't (the program never enters the loop). You need to ensure that there's an unconditional return statement somewhere in your function.
Since the loop terminates early via return when a match is found, and since all patients need to be checked otherwise, you should simply move the return false; out of the loop. Right now the logic isn't sound.
Also, make sure you indent your code properly, for those you want help from, and for your own sanity.
Code:bool check_if(informationT a[], int size)
{
int i;
char sur[20], name[15];
printf("Give patient's last name \n");
gets(sur);
printf("Give patient's first name \n");
gets(name);
for (i = 0; i < size; i++)
{
if ((sur == a[i].epwnymo) && (name == a[i].onoma))
return true;
else
return false;
}
}
More problems:
1) We cannot see what the struct, "informationT" is. You have not provided a small program sufficient to allow us to see and test the program.
2) DO NOT use gets()!!! Please use fgets() or other functions instead. See: Why gets() is bad / Buffer Overflows
3) Without seeing the details of the struct, it appears you are attempting to compare two strings with the '==' operator. You need to use the strcmp() function to compare strings.Code:if ((sur == a[i].epwnymo) && (name == a[i].onoma))
i have recently learned fgets, so i have to get familiar with it.
here is the sturct.
just used strcmp too, i always get the answer as false.Code:typedef struct{ char epwnymo[20]; //surname
char onoma[15]; //name
char dieythinsi[30]; //adress
int poso_plirwmis; //money he payed to hospital
}informationT;
just the code a bit more
here it is
Code:
bool check_if(informationT a[],int size){
int i;
char sur[20],name[15];
bool x;
printf("Give patient's last name \n");
gets(sur);
printf("Give patient's first name \n");
gets(name);
for (i=0; i<size; i++){
if ((strcmp(sur,a[i].epwnymo)) && strcmp(name,a[i].onoma) ){
x = true;
break;
}
else{
x = false;
break;
}
}
return x;
}
Code:
bool check; // it's in the top of the program
check = check_if(stoixeia,N); if (check){
printf("PATIENT FOUND");
}
else{
printf("PATIENT NOT FOUND");
}
In your code:
From the output from `man strcmp`:Code:if ((strcmp(sur,a[i].epwnymo)) && strcmp(name,a[i].onoma) )
I think the statement above is the opposite of what you want! Please run tests to confirm, as you still have not provided us with a complete program we can compile and test ourselves.Quote:
The strcmp() function compares the two strings s1 and s2. It returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2.
If "sur" , and "a[i].epwnymo" are exactly the same, then strcmp() would return, "0", and the if statement would be false!
EDIT: Also, each function should do one thing, and one thing only.
For the function "bool check_if(informationT a[],int size)", I would expect that this only "Checks" some data, not Input data, and then compare that data. This should be split into at least two different functions.
Hi,
your second problem lies in this part.
You check if the patient is found, but found or not found in both cases you use a break statement to leave the loop.Code:for (i=0; i<size; i++){
if ((strcmp(sur,a[i].epwnymo)) && strcmp(name,a[i].onoma) ){
x = true;
break;
}
else{
x = false;
break;
}
}
Cheers
here is the whole programCode:#include <stdio.h>#include "string.h"
#include "simpio.h"
#include "stdbool.h"
#define N 3
typedef struct{
char epwnymo[20];
char onoma[15];
char dieythinsi[30];
int poso_plirwmis;
}informationT;
void eisagwgi_stoixeiwn(informationT a[],int size);
void print_katastasi(informationT a[],int size,char kliniki[]);
informationT max(informationT a[],int size);
void print_best_astheni(informationT a);
int calc_sum(informationT a[],int size);
void emfanisi_astheni(informationT asthenis);
bool check_if(informationT a[],int size);
int main(){
informationT stoixeia[N],asthenis,patient;
int i,eispraksi;
char kliniki1[] = "Elpis";
char kliniki2[] = "Galinos";
bool check;
eisagwgi_stoixeiwn(stoixeia,N);
print_katastasi(stoixeia,4,kliniki1);
print_katastasi(stoixeia,3,kliniki2);
asthenis = max(stoixeia,N);
print_best_astheni(asthenis);
eispraksi = calc_sum(stoixeia,N);
for (i=0; i<100; i++){ printf("-"); }
printf("\n");
printf("Sinoliki eispraksi %d\n",eispraksi);
for (i=0; i<100; i++){ printf("-"); }
for (i=0; i<2; i++){printf("\n");}
patient = stoixeia[0];
emfanisi_astheni(patient);
printf("\n");
check = check_if(stoixeia,N);
if (check){
printf("PATIENT FOUND");
}
else{
printf("PATIENT NOT FOUND");
}
return 0;
}
void eisagwgi_stoixeiwn(informationT a[],int size){
int i;
for (i=0; i<size; i++){
printf("dwse ta stoixeia tou astheni %d\n",i+1);
printf("Dwse epwnymo ");
gets(a[i].epwnymo);
printf("Dwse onoma ");
gets(a[i].onoma);
printf("Dwse dieythinsi ");
gets(a[i].dieythinsi);
printf("Dwse poso plirwmis ");
a[i].poso_plirwmis = GetInteger();
}
for (i=0;i<2;i++){printf("\n");}
}
void print_katastasi(informationT a[],int size,char kliniki[]){
int i;
printf("------ %s ------\n",kliniki);
printf("%-5s %-9s %-11s %-16s \n","EPWNYMO","ONOMA","DIEYTHINSI","POSO" );
for (i=0; i<100; i++){
printf("-");
}
printf("\n");
for (i=0; i<size; i++){
printf("%-5s %-9s %-11s %-14d \n",a[i].epwnymo,a[i].onoma,a[i].dieythinsi,a[i].poso_plirwmis);
}
for (i=0; i<2; i++){ printf("\n"); }
}
informationT max(informationT a[],int size){
int i;
informationT best_asthenis;
strcpy( best_asthenis.dieythinsi,a[0].dieythinsi);
strcpy(best_asthenis.epwnymo,a[0].epwnymo);
strcpy(best_asthenis.onoma,a[0].onoma);
best_asthenis.poso_plirwmis = a[0].poso_plirwmis;
for (i=1; i<size; i++){
if (best_asthenis.poso_plirwmis < a[i].poso_plirwmis)
strcpy( best_asthenis.dieythinsi,a[i].dieythinsi);
strcpy(best_asthenis.epwnymo,a[i].epwnymo);
strcpy(best_asthenis.onoma,a[i].onoma);
best_asthenis.poso_plirwmis = a[i].poso_plirwmis;
}
return best_asthenis;
}
void print_best_astheni(informationT a){
int i;
printf("Kalhteros asthenis \n");
printf("Epwnymo Onoma Dieythinsi Poso \n");
for (i=0; i<100; i++){
printf("-");
}
printf("\n");
printf("%-7s %-20s %-10s %-5d \n",a.epwnymo,a.onoma,a.dieythinsi,a.poso_plirwmis);
for (i=0; i<2; i++){ printf("\n");}
}
int calc_sum(informationT a[],int size){
int sum,i;
sum = 0;
for (i=0; i<size; i++){
sum += a[i].poso_plirwmis;
}
return sum;
}
void emfanisi_astheni(informationT asthenis){
printf("%-7s %-20s %-10s %-5d \n",asthenis.epwnymo,asthenis.onoma,asthenis.dieythinsi,asthenis.poso_plirwmis);
}
bool check_if(informationT a[],int size){
int i;
char sur[20],name[15];
bool x;
printf("Give patient's last name \n");
gets(sur);
printf("Give patient's first name \n");
gets(name);
for (i=0; i<size; i++){
if ((strcmp(sur,a[i].epwnymo)) && strcmp(name,a[i].onoma) ){
x = true;
break;
}
else{
x = false;
break;
}
}
return x;
since i'm doing an exercise for uni, it asks me to ask for information in the function, that's why i do it inside
Please make the corrections that we have recommended, first, test your code THOROUGHLY, then come back to us if you still have problems.
Also, please turn on, and/or turn up your compiler's warning levels to the highest settings, and correct any errors or warning that you see, before asking for additional help.
i did it, in case anyone else has any similar problemCode:
bool check_if(informationT a[],int size){
int i;
char sur[20],name[15];
bool x;
printf("Give patient's last name \n");
gets(sur);
printf("Give patient's first name \n");
gets(name);
for (i=0; i<size; i++){
if ( (strcmp(sur,a[i].epwnymo) == 0) && strcmp(name,a[i].onoma) == 0 ){
x = true;
}
else{
x = false;
}
}
return x;
}
thanks everyone.
That is good to hear, but as Guest noted in post #2, you really need to format your code properly, especially where indentation is concerned. For example:
rstanley made it clear in post #3 that you must not use the gets function. This function is inherently vulnerable to buffer overflow, and in fact it has been removed from the newest version of the C standard library.Code:bool check_if(informationT a[], int size) {
int i;
char sur[20], name[15];
bool x;
printf("Give patient's last name \n");
gets(sur);
printf("Give patient's first name \n");
gets(name);
for (i = 0; i < size; i++) {
if ((strcmp(sur, a[i].epwnymo) == 0) && strcmp(name, a[i].onoma) == 0) {
x = true;
}
else {
x = false;
}
}
return x;
}
Next, it looks like you have made an oversight in your implementation of check_if: the same set of data could well result in check_if returning true under one ordering, and result in check_if returning false under another ordering. The reason is that your loop simply sets x to true or false, and then goes on to the next iteration.
Typically, such a function would be designed to return true if and only if a condition holds true for all the elements, or it would be designed to return true if and only if a condition holds true for any element. For the former, a typical approach would be:
For the latter, a typical approach would be:Code:for element in container
if condition is false for the element
return false
return true
Of course, instead of returning within the loop, you could initialise a flag (in this case your variable named x) to the default return value, then set it within the loop and break out of the loop once it is set.Code:for element in container
if condition is true for the element
return true
return false
Note that "check_if" is a very generic name. You should use a more descriptive name, e.g., "check_if_patient_exists". Likewise, while "i" as a loop/array index is fine, "x" is not a descriptive name. Even a relatively generic name like "flag" would be better, though it would be best if you could use a name related to the purpose of the function.
while i use "gets" the result is correct. if i use fgets the result is wrong.
Code:bool check_if(informationT a[],int size){int i;
char sur[20],name[15];
bool flag;
printf("Give patient's last name \n");
fgets(sur,sizeof(sur),stdin);
printf("Give patient's first name \n");
fgets(name,sizeof(name),stdin);
for (i=0; i<size; i++){
if ( (strcmp(sur,a[i].epwnymo) == 0) && strcmp(name,a[i].onoma) == 0 ){
flag = true;
}
else{
flag= false;
}
}
return flag;
Did you remove the end of line character from the string when using fgets()? With the fgets() function the end of line character is considered a valid character and is "added" to the string if there is room for this character. You need to manually remove this character if it is not needed.
Jim
fgets will store the newline from entering the line if there is space to store it, hence you should remove it, e.g.,Quote:
Originally Posted by Giwrgows x
Code:name[strcspn(name, "\n")] = '\0';
triedstill wrong resultCode:name[strcspn(name, "\n")] = '\0';
tried this also, but the same
Code:if (sur[strlen(sur) - 1] == '\n') {
sur[strlen(sur) - 1] = '\0';
}
What is the current code of your function?
Code:bool check_if(informationT a[],int size){int i;
char sur[20],name[15];
bool flag;
printf("Give patient's last name \n");
fgets(sur,sizeof(sur),stdin);
printf("Give patient's first name \n");
fgets(name,sizeof(name),stdin);
name[strcspn(name, "\n")] = '\0';
sur[strcspn(sur, "\n")] = '\0';
for (i=0; i<size; i++){
if ( (strcmp(sur,a[i].epwnymo) == 0) && strcmp(name,a[i].onoma) == 0 ){
flag = true;
}
else{
flag= false;
}
}
return flag;
}
That looks correct, except that you have not fixed the logic that I pointed out, so that could be the source of the problem.
even like this, i have the same resultCode:
for (i=0; i<size; i++){
if ( (strcmp(sur,a[i].epwnymo) == 0) && strcmp(name,a[i].onoma) == 0 ){
flag = true;
}
}
flag = false;
return flag;
}
That is simply incorrect: you are always setting the flag to false. Here is how I might write it:
If it still does not work, then it would not have worked with gets. If it worked with gets, then you did something wrong such that the code that you actually compiled and ran is different from the code that I posted here.Code:bool check_if(informationT a[], int size)
{
char surname[20];
char name[15];
int i;
printf("Give patient's last name \n");
if (!fgets(surname, sizeof(surname), stdin))
{
printf("Error: could not read patient's last name!\n");
return false;
}
surname[strcspn(surname, "\n")] = '\0';
printf("Give patient's first name \n");
if (!fgets(name, sizeof(name), stdin))
{
printf("Error: could not read patient's first name!\n");
return false;
}
name[strcspn(name, "\n")] = '\0';
for (i = 0; i < size; i++)
{
if (strcmp(surname, a[i].epwnymo) == 0 && strcmp(name, a[i].onoma) == 0)
{
return true;
}
}
return false;
}
it worked.
could you please explain the difference between the 2 codes that made my one not work?
As I mentioned, you are always returning false. This is what happens when you write:
If you want to set flag to false, you should do so before the loop.Code:flag = false;
return flag;
yes but,
shouldn't flag be true if the statement is true?Code:if (statement){
flag = true;
//otherwise flag = false
return flag;
What do you mean? Refer to my post #10. What is check_if supposed to do?
it's supposed to get the name and the surname of someone and check if with these details, a patient in the hospital exists and return he is found otherwise he is not found
But that's not what you were doing.
You were doing:
That flag = false was not part of your if statement.Code:if(statement)
{
flag = true;
}
flag = false;
return false;
Consistent use of indentation would help you see the problem.
Your code reformatted:
JimCode:for (i=0; i<size; i++) {
if ( (strcmp(sur,a[i].epwnymo) == 0) && strcmp(name,a[i].onoma) == 0 ) {
flag = true;
}
}
flag = false;
return flag;
}
Great. So what that means is that your condition is "is a patient in the hospital". You want to return true if and only if there exists a patient that satisfies this condition.Quote:
Originally Posted by Giwrgows x
So, how would you go about this? If you recall first order logic, what you can do is to make an absolute statement:
All patients in the hospital is not this someone.
This is equivalent to saying:
That is, no such patient will be found.Code:bool found = false;
Now, to disprove an absolute statement, you only need to find a counterexample. So, you search the array of patients to find a patient that matches this someone:
When you find that someone, you have your counterexample, so you set found = true and stop searching: you don't need more counterexamples to disprove the absolute statement. If you did not find a match, well, the loop will end without setting found = true, and it turns out that the absolute statement is true, so you:Code:for (i = 0; i < size; i++)
{
if (strcmp(surname, a[i].epwnymo) == 0 && strcmp(name, a[i].onoma) == 0)
{
found = true;
break;
}
}
where found would have remained false. But if you did find a match, found = true, so you would have returned true, which is correct.Code:return found;
anyway, thanks everyone for the help and your time, and huge thanks for forcing me to use fgets(), have a nice night.
Giwrgos