Parsing item list line by line then character by character - c

Question

I have to parse a game file that has this format:
ItemID = 3288 # This is a comments and begins with '#' character.
Name = "a magic sword"
Description = "It has some ancient runic inscriptions."
Flags = {MultiUse,Take,Weapon}
Attributes = {Weight=4200,WeaponType=1,WeaponAttackValue=48,WeaponDefendValue=35}
# A line can also begin with this character and it should be ignored.
and I have to parse it's data and put them into variables. I have tried many things, and I've been told that I will have to read the file line by line, then read each line character by character (so I'm able to read until '#' character) and then read the result word by word following the pattern. I have done this:
void ParseScriptFile(FILE* File) {
char Line[1024];
while (fgets(Line, sizeof(Line), File)) {
}
fclose(File);
}
I think I should read the lines inside the while loop but I don't know how would I read until # character is reached and if it does not exist just continue looping line through line. Is there an easy way to do this?

Answer 1

Use sscanf, like I did two for you
void ParseScriptFile(FILE* File) {
char Line[1024];
int ItemID; // variable to store ItemId
char name[40]; // string to store Name
while (fgets(Line, sizeof(Line), File)) {
sscanf(Line, "ItemID = %d", &ItemID);
sscanf(Line, "Name = %[^n]s", name); // ^n upto newline
}
printf("ItemId= %d\n", ItemID);
printf("Name= %s", name);
fclose(File);
}

Answer 2

Here's more or less workable code. Reading lines with fgets() is correct. You can then eliminate empty lines and comment lines trivially. If the line ends with a comment, you can convert the # into a null byte to ignore the comment. Then you need to scan for the entries name field (assume there are no spaces in the name part, to the left of the equals sign), and the = and the value on the right.
#include <stdio.h>
#include <string.h>
static
void ParseScriptFile(FILE *File)
{
char Line[1024];
while (fgets(Line, sizeof(Line), File))
{
if (Line[0] == '#' || Line[0] == '\n')
continue;
char *comment_start = strchr(Line, '#');
if (comment_start != NULL)
*comment_start = '\0';
char name[64];
char value[1024];
if (sscanf(Line, " %63s = %1023[^\n]", name, value) == 2)
printf("Name = [%s] Value = [%s]\n", name, value);
else
printf("Mal-formed line: [%s]\n", Line);
}
fclose(File);
}
int main(void)
{
ParseScriptFile(stdin);
return 0;
}
The program reads from standard input. An example run from your data file yielded:
Name = [ItemID] Value = [3288 ]
Name = [Name] Value = ["a magic sword"]
Name = [Description] Value = ["It has some ancient runic inscriptions."]
Name = [Flags] Value = [{MultiUse,Take,Weapon}]
Name = [Attributes] Value = [{Weight=4200,WeaponType=1,WeaponAttackValue=48,WeaponDefendValue=35}]
Note the space at the end of the ItemID value; there was a space before the # symbol.
If you need to handle strings that could themselves contain # symbols, you have to work harder (Curse = "You ###$%!" # Language, please!). Parsing an entry such as the value for Attributes is a separate task for a separate function (callable from this one). Indeed, you should be calling one or more functions to process each name/value pair. You probably also need some context passed to the ParseScriptFile() function so that the data can be saved appropriately. You wouldn't want to contaminate clean code with unnecessary global variables, would you?