C: File parsing without losing white space

Question

I am parsing a file for particular keyword matching by C program, here is my sample code...

#include <stdio.h>

int main() { 

    FILE *infile = fopen("Somefile.txt", "r");

    char buffer[256];
    char value[128];

    while (fgets(buffer, sizeof(buffer), infile))
        if (1 == sscanf(buffer, " x = %s", value))
            printf("Value = %s\n", value);
    return 0;
}

Somefile.txt

some junk
#a comment
a = 1 ; a couple other variables.
b = 2
x = 3
 x = 4
x=5
x = Hi hello

Output:

Value = 3
Value = 4
Value = 5
Value = Hi

Problem : when x contain the value like "Hi Hello", then it just parsing "Hi" only, I want to parse whole value of x without loosing space.

please suggest me solution for it.

Thanks.

Answer 1

In this line of your code:

if (1 == sscanf(buffer, " x = %s", value))

%s means to read in one word.

If you want to read in the rest of the line, use %[^\n]s like this:

if (1 == sscanf(buffer, " x = %[^\n]s", value))

Answer 2

The first thing to do is back off on sscanf. If you read the man page, scanf treats spaces as specifications that say "you'll have some white space here, it's not important." Then other characters are specifications for literals. The effect is that that format spec is something like "any amount of while space, then an x, then more white space, then an '=', then more white space, then a string, and now return the string."

What you're really trying to do here is some lightweight parsing. You'll probably do better to read each line and scan it with a simple finite state machine, ie,

while not end of file
   while not end of line
      get next character
      if char == ";" -- comment
         break
      if char is a letter
         parse an assignment

and so on.