/*
Implement a C program that receives through the command line a string as input.
The program must transform the content of the string in uppercase letters and print it on the screen.
The option '-c <number>' between the name of the program and the string is used to convert 
and print only the first <number> characters of the string.
*/

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

#define LEN 50


int main(int argc, char *argv[]) {
    int i;
    char s[LEN+1];
    int string_length;

    /* Running the program as follows:
       prog_name.exe -c 4 sTriNg
       the variables *argv[] and argc contains the following values:

    argv[0]="prog_name.exe"
    argv[1]="-c"
    argv[2]="4"
    argv[3]="sTriNg"
    argc=4

    And the output of the program will be STRI
    */

    
    if(argc==4){ /* If the user has specified the option -c */

      string_length = atoi(argv[2]);
      strncpy(s, argv[3], string_length);
      s[string_length] = '\0';

    }else{ /* If the only argument is <string> */

      strcpy(s, argv[1]);
      string_length = strlen(s);

    }

    for(i=0; i<string_length; i++){
      s[i] = toupper(s[i]);
    }
    
    printf("The resulting string is: %s\n", s);

    return 0;
}