I'm new to string and file operations in C and I have a text file file.txt with below data.

I'm reading a text file which contains below information

1.#comment
2.Name="Audi"
3.Class="Premium"
4. Cost="High"
5.   #

I wanted to store contents of this file into a buffer with below conditions:

1. skip lines containing '#' in it which are for comments
2. skip lines which are starting with white space.

while writing to the buffer.

I have used fgets() to read each line by line which checks for '#' presence in it

My sample code is below:

char buffer[64];
    
    FILE* fp= fopen("file.txt", "r"); 
    if (NULL == fp) {
            printf("file can't be opened \n");
        }
    else
    {
     
    while (fgets(buffer, sizeof(buffer), fp)) 
    
    {                                                                                                                                   
        if(buffer[0]=='#')
        {
            continue;
        }                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   printf("%s", buffer); 
     }  
    }

This code works fine if first character of line is #(1st line), but I wanted to skip line whenever I get a # in the line not only first one(5th line in text file needs to be skipped). Similarly I wanted to skip line if I have white space in line(4th line). I'm getting stuck here and unable to proceed further. Is there an efficient way to do the same? Please support

CodePudding user response：

use strchr

while (fgets(buffer, sizeof(buffer), fp)) 

{                                                                                                                                   
    if(strchr(buffer, '#') != NULL)
    {
        continue;
    }                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
     printf("%s", buffer); 
 }  
}

it returns NULL if char not in string

CodePudding user response：

Assuming that a line that contains a '#' is retained if it is not the first non-white-space letter:

To skip if line begins with a white-space

    if(isspace(buffer[0])) continue;

Otherwise to skip if line begins with a #

    if(buffer[0] == '#') continue;

Together

while (fgets(buffer, sizeof(buffer), fp)) { 
  unsigned char first = buffer[0];
  if(isspace(first) || (first == '#')) continue;
  ...
}

Otherwise search for a '#' as suggested by pm100.