Parse Flags

Task

• Implement a program that accepts command-line flags:
  • -d <delim> → use custom delimiter string (default: space)
  • -s <sep> → use custom output separator (default: newline)
• Read lines from stdin, tokenize by delimiter, output tokens separated by separator
• Flags can appear in any order

Command Format: ./parse_flags [-d <delim>] [-s <sep>]

IMPORTANT

Process flags before reading stdin. After processing all flags, read from stdin

TIP

• Use strtok() with the delimiter string
• Parse argv to find flags and their values
• Default delimiter: " " (space)
• Default separator: "\n" (newline)
• Print separator BETWEEN tokens, not after the last one

---

Example

$ gcc parse_flags.c -o parse_flags
$ ./parse_flags
hello world test
hello
world
test
$ ./parse_flags -d ":"
key:value:pair
key
value
pair
$ ./parse_flags -s "\t"
hello world test
hello	world	test
$ ./parse_flags -d ":" -s " | "
a:b:c
a | b | c
$ ./parse_flags -s "," -d "|"
one|two|three
one,two,three

---

Code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int main(int argc, char **argv)
{
    char *delim = " "; // default delimiter
    char *sep = "\n";  // default separator
 
    for(int i = 1; i < argc; i++){
        if(strcmp(argv[i], "-d") == 0){
            i++;
            delim = argv[i];
        }
        if(strcmp(argv[i], "-s") == 0){
            i++;
            sep = argv[i];
        }
    }
 
    // After parsing flags, read from stdin
    char buffer[1001];
 
    while (fgets(buffer, sizeof(buffer), stdin) != NULL)
    {
        // Remove trailing newline
        size_t len = strlen(buffer);
        if (len > 0 && buffer[len - 1] == '\n')
        {
            buffer[len - 1] = '\0';
        }
 
        char* word = strtok(buffer, delim);
        while(word != NULL){
            printf("%s", word);
            word = strtok(NULL, delim);
            if (word != NULL) {
                printf("%s", sep);
            }
        }
    }
 
    return 0;
}