How to properly terminate strings in C programming? [closed] - c

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I'm using scanf to scan 5 product names and store them in a string. However, when i print them, the last one is always printed as ♣. Where am i going wrong ?
I am trying to take in the id, name and prices of 5 products and print them using structures. However the last product name is always printed as ♣. I realised that this may be due to improper terminating of the string, and tried the solutions provided to such questions.
I saw another similar question on strings and tried to terminate the string properly by doing, char name[50]={'0'}; in my code. This part is within the structure part of the code.
struct product
{
int id;
char name[50];
int price;
};
void main()
{
struct product p [5];
int i,a;
for(i=1;i<=5;i++)
{
printf("Enter the id no., name and price of the product %d\n",i);
scanf("%d%s%d",&p[i].id,&p[i].name,&p[i].price);
}
printf("The id no., name and price of the product %d are\n",i);
for(i=1;i<=5;i++)
{
printf("\t%d\t%s/0\t%d\n",p[i].id,p[i].name,p[i].price);
}
}
The final output, that is p[5].name ,should've been what i had entered, but is, however, ♣.
And if i try to terminate the code by entering: char name[50]={'\0'};
it puts up an error message over the '=' saying that it expected a ';'.

Answer 1

The problem is not with termination of strings. [Note 1]
Your problem is that arrays in C start at index 0, not index 1. So the elements in p are p[0] through p[4] and so p[5] references random memory. C does not check that array indexes are valid, and using invalid ones leads to odd bugs like this one.
scanf certainly NUL-terminates strings, which is why I said that termination is not a problem. However, it doesn't know how much memory you've reserved for the string, so it could well overwrite random memory if the string entered by the user is too long. Better to use the format "%d%49s%d" (in this case) to limit the string read to 49 characters. (You can't fit a 50-character string in a 50-element array precisely because you need to leave space for the terminating NUL.)
However, you also need to check the return value of scanf. That function returns the number of successful conversions, which in this case must be three. If it returns a smaller number, that means one of the conversions failed, and if a numeric conversion fails, the offending character (perhaps a letter) will still be the next input character, so the next %d conversion will also fail.
Notes:
If you want to store a NUL in a string, you would do something like;this, assuming you know where the string ends:
p[i].name[len] = `\0`;
You can declare and initialise a character array so that all its elements are 0:
char name[50] = { '\0' };
But you can't put an initialiser inside the definition of a struct. The struct declaration only defines the general form of a composite object; it doesn't declare any instances of that object so there is nothing to initialise.

Answer 2

Looks great. Remember that arrays start from 0. Change for loops to indexes 0 - 4.
for(i = 0; i < 5; i++)
{
printf("Enter the id no., name and price of the product %d\n",i);
scanf("%d%s%d",&p[i].id,&p[i].name,&p[i].price);
}
In general, I highly recommend using fgets for input of strings from user in order to avoid the risks of scanf + adds the NULL at end.
#include <string.h>
for(i = 0; i < 5; i++)
{
printf("Enter the id no., name and price of the product %d\n",i);
scanf("%d",&p[i].id);
fgets(p[i].name, 50, stdin);
scanf("%d",&p[i].price);
}
More about fgets -> https://www.geeksforgeeks.org/fgets-gets-c-language/