Invocation of structure member info display function spits garbled characters - c

Question

I created a structure that goes as follows:
typedef struct
{
char name[20];
char country[20];
int age;
float height;
} details;
Accompanying the structure definition are two functions that accept and display the details of the structure's members respectively:
void enter_details(details d1)
{
printf("Enter your name: ");
gets(d1.name);
printf("Enter your country: ");
gets(d1.country);
printf("Enter your age: ");
scanf("%d",&d1.age);
printf("Enter your height (in meters): ");
scanf("%d",&d1.height);
}
void show_details(details d1)
{
printf("Name: ");
puts(d1.name);
printf("\nCountry: ");
puts(d1.country);
printf("\nAge: %d",d1.age);
printf("\nHeight: %.2f m",d1.height);
}
The declaration of a structure object in the main() segment is relatively straightforward and goes as follows:
details d1;
While the compiler doesn't spit any errors as such, and neither does the invocation of the function that accepts information for the structure's members, invocation of the show_details() function spits out nothing but garbled, gibberish characters. What is causing this anomaly?

Answer 1

In C, arguments of a function are passed by value, not by reference, meaning that the argument you pass will be copied. So what you are dealing with inside your function is a copy of your object, not the actual object. In order to refer to the actual object, you need to pass a reference.
Also, avoid using scanf() (and gets()) to read input. Use fgets() instead.
So, you should change your code to:
void enter_details(details *d1)
{
printf("Enter your name: ");
getstring(d1->name, sizeof(d1->name)));
printf("Enter your country: ");
getstring(d1->country, sizeof(d1->country));
printf("Enter your age: ");
getint(&d1->age);
printf("Enter your height (in meters): ");
getint(&d1->height);
}
An alternative to scanf() to read a string:
char *getstring(char *str, int size)
{
if (!fgets(str, size, stdin)) {
fprintf(stderr, "Input error\n");
return NULL;
}
str[strcspn(str, "\n")] = '\0'; // fgets() reads the ending '\n' so null-terminate the string
return str;
}
And to read an int:
int getint(int *i)
{
char buffer[255];
if (!fgets(buffer, 255, stdin)) {
fprintf(stderr, "Input error\n");
return 0;
}
str[strcspn(str, "\n")] = '\0';
if (sscanf(buffer, "%d", i) != 1)
return 0;
return 1;
}

Answer 2

Do not use gets. Use fgets instead. fgets(d1.name, sizeof(d1.name), stdin);
You need to pass the reference to the struct otherwise you will work on the local copy of the structure. You can also return the structure.
void enter_details1(details *d1)
{
printf("Enter your name: ");
fgets(d1 -> name, sizeof(d1 ->name), stdin);
printf("Enter your country: ");
fgets(d1 -> country, sizeof(d1 -> country), stdin);
printf("Enter your age: ");
scanf("%d",&d1 ->age);
printf("Enter your height (in meters): ");
scanf("%d",&d1 ->height);
}
details enter_details(void)
{
details d1;
printf("Enter your name: ");
fgets(d1.name, sizeof(d1.name), stdin);
printf("Enter your country: ");
fgets(d1.country, sizeof(d1.country), stdin);
printf("Enter your age: ");
scanf("%d",&d1.age);
printf("Enter your height (in meters): ");
scanf("%d",&d1.height);
retunrn d1;
}
usage:
int main(void)
{
details d;
enter_details1(&d);
//or
d = enter_details();
/* .... */
}
BTW I hope that you know that height can be only entered in full meters. No fractions