C - Read from .INI file and pass values to vars - c

Question

I'm doing a project for school and I need to read from an .INI file to start my vars for the game. Problem is, I cannot seem to understand how strtok works and I'm really confused at this point.
I know I'm returning an empty struct because I have no idea how to put the specific values into the vars!
Here's my read_from_config.h
#ifndef READ_FROM_CONFIG_H
#define READ_FROM_CONFIG_H
#define MAXSTR 500
typedef struct {
unsigned int xdim;
unsigned int ydim;
unsigned int nzombies;
unsigned int nhumans;
unsigned int nzplayers;
unsigned int nhplayers;
unsigned int turns;
} CONFIG;
CONFIG read_config(char *argv[]);
#endif
And here is my read_from_config.c
#include "read_from_config.h"
#include "example.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
CONFIG read_config(char *argv[]) {
char str[MAXSTR];
FILE *fp = NULL;
char *filename = argv[1];
char *token;
fp = fopen(filename, "r");
if (fp == NULL) {
fprintf(stderr, "Não foi possível abrir ficheiro de configuração.");
fprintf(stderr, "\nModo de uso: ./program_name config.ini");
}
while (fgets(str, MAXSTR, fp) != NULL) {
for (int i = 0; i != '\0'; i++) {
char *equal = strpbrk (str, "=");
if (equal) {
token = strtok(str, "=");
}
}
}
printf("%d", token[0]);
CONFIG config;
return config;
}
CONFIG.INI
; Dimension of the grid
xdim=20
ydim=20
; Inicial number of zombies and humans
nzombies=20
nhumans=20
; Number of zombies and humans controlled by players
nzplayers=0
nhplayers=1
; Number of maximum turns
maxturns=1000

Answer 1

The function strtok take a string only the first time it gets called. All
subsequent calls must be passed with NULL
man strtok
#include <string.h>
char *strtok(char *str, const char *delim);
DESCRIPTION
The strtok() function breaks a string into a sequence of zero or more nonempty tokens.
On the first call to strtok(), the string to be parsed should be specified in str.
In each subsequent call that should parse the same string, str must be NULL.
Example:
char line[] = "a,b,c,d,e,f\n"; // to simulate an fgets line
char *token = strtok(line, ",\n"); // you can add \n to the separator
// to get rid of the \n at the end
puts(token); // prints a
while(token = strtok(NULL, ",\n"))
puts(token); // prints b then c etc..
Keep in mind that strtok modifies the source, this is going to fail:
strtok("a,b,c", ",");
because string literals are not modifiable. In that case you have to make a copy
to a char[] or a dynamic allocated char*.
If you need to have the source intact after the parsing, then you definitively
need to make a copy.
In your code you do:
printf("%d", token[0]);
That's not incorrect but perhaps not what you want to do. This line doesn't
print the first character, it prints the ascii value of the first character.
This
printf("%c", token[0]);
will print the first character.
Also you are doing
CONFIG read_config(char *argv[]) {
...
CONFIG config;
return config;
}
You are returning an uninitialized CONFIG object, you are ignoring the parsing
and nothing is set in your config object.
Your parsing is also a little bit strange.
for (int i = 0; i != '\0'; i++)
The loop exits immediately because 0 == '\0'! I don't understand what you are
trying to do with it.
I would first create a helper function to populate the values of the config, see
set_config_val. Then you can parse it like this:
CONFIG read_config(char *argv[]) {
...
const char *delim = "=\n";
CONFIG config;
while (fgets(str, MAXSTR, fp) != NULL) {
if(strchr(str, '='))
{
char varname[100];
int value;
token = strtok(line, delim);
strcpy(varname, token);
token = strtok(NULL, delim);
value = atoi(token);
set_config_val(&config, varname, value);
} else {
fprintf(stderr, "Skipping line, no = found");
}
}
fclose(fp);
return config;
}
void set_config_val(CONFIG *config, const char *key, int val)
{
if(config == NULL)
return;
if(strcmp(key, "xdim") == 0)
config->xdim = val;
else if(strcmp(key, "ydim") == 0)
config->ydim = val;
...
}