Thread: How come I can print the entire string but, not an individual character?

Hi Guys, I'm trying to parse a log that looks like this:

Code:

data,b1a571,3324 d,123.46,987.65
[2022-09-01 16:08] ,RSSI: -25
[2022-09-01 16:08] ,Sent a reply
[2022-09-01 16:08] ,mdata,b1a571,3324 d,123.46,987.65
[2022-09-01 16:08] ,RSSI: -25
[2022-09-01 16:08] ,Sent a reply
[2022-09-01 16:08] ,mdata,b1a571,3324 d,123.46,987.65
[2022-09-01 16:08] ,RSSI: -25
[2022-09-01 16:08] ,Sent a

Notice the first and last lines are often partial entries. If the first line doesn't begin with a '[', I intend to append it to the last line of the prior log.

If the last entry ends without a '\n', I'm planing to save it to a temporary string and append the first line of the next log. Am I making sense? I'm a novice C coder but, really enjoying it.

Here's my code that fails to figure out if the first line begins with a '['.

Code:

#include <stdio.h>
#include <string.h>


// How to read a text file line by line in C Programming - YouTube


char fpath4[100] = "C:/work/arduino/teraterm-4.106/logs/";
char fname4[] = "logToParse";


void main(){
    strcat(fpath4, fname4);                     // put the log name at the end of the path
    FILE *the_file = fopen(fpath4, "r");        // open the file Read Only
    if(the_file == NULL){                       // if the file doesn't exist, display an error
        perror("\nUnable to open the file");
        exit(1);                                // exit the program
    }
    char line[100];
    //while(fgets(line, sizeof(line), the_file)){ // while there is a line : fgets gets a single line
        fgets(line, sizeof(line), the_file);
        printf("\n%s", line);                   // prints the entire line of the log
        printf("\n%s", line[0]);                // DOES NOT WORK
    //}
    fclose(the_file);
    //fclose(???);
    return 0;
}

I'm try to read only the first character of 'line' to see if it is a '['. How come

Code:

printf("\n%s", line[0]);

does not work? Do I need to convert 'line' to an array first or something? Thank you.

doh!!! %c!

Code:

printf("%c", line[0]);

%s, prints the entire string
%c, prints one character

Once again, please see my response in previous thread!

Hey rstanley, Thank you for the response. I have read two books on C and purchased another today: Amazon.com I'm drinking from a fire hose! I forget most of what I'm reading but, still a lot sticks. Please forgive my novice questions. Believe me, I'm trying. It's just that I'm a bit thick in the head. I will be more careful.

Originally Posted by mpatters

Hey rstanley, Thank you for the response. I have read two books on C and purchased another today: Amazon.com I'm drinking from a fire hose! I forget most of what I'm reading but, still a lot sticks. Please forgive my novice questions. Believe me, I'm trying. It's just that I'm a bit thick in the head. I will be more careful.

Good book for its time, but not current. It covers the C89/90 C Standard, but superseded by C99, C11, C18 (Sometimes listed as C17), and the next version of the C Standard "Cxx".

The three books I listed are more up to date, and recommended over K&R, 2nd edition.

Originally Posted by rstanley

Good book for its time, but not current.

By "its time" you mean 1988, or 34 years ago. That's an eternity in computers!

(I noticed the edition listed on that Amazon page is published by Pearson India. There seems to be a trend of using old technology like Borland Turbo C for DOS in some Indian computer programming courses. Maybe they've upgraded to the C90 standard recently?)