Gfrktyl

I wrote a Program that gets the input from a txt file and stores the input in an array.
After that I remove the spaces from each string so that it's easier for me to compare the string values in the array reds against the string value in the array string card.

The array red must contain all the elements of the array stringcard or else an error message will be printed. It doesn't matter if the elements in the input file are in order.

#include <stdio.h> 

#include <string.h> 

#include <stdlib.h>

#define max 13

#define stringlength 8



//removes spaces

char * removechar(char str, int ch) {



  char * cpos = str;



  while ((cpos = strchr(cpos, ch))) {

    strcpy(cpos, cpos + 1);

  }

  return str;

}



int all_match( char **table1, const char **table2, size_t t1size, size_t t2size)

{

    for(size_t t1index = 0; t1index < t1size; t1index++)

    {

        int match = 0;

        for(size_t t2index = 0; t2index < t2size; t2index++)

        {

            match = match || !strcmp(table1[t1index], table2[t2index]);

            if(match) {

            break;

        }

        }

        if(!match){

            printf("error");

             return 0;

         }

    }

    return 1;

}



int main(int argc, char ** argv) {



const char *stringcard = {

  "REDAn",

  "RED2n",

  "RED3n",

  "RED4n",

  "RED5n",

  "RED6n",

  "RED7n",

  "RED8n",

  "RED9n",

  "RED10n",

  "REDJn",

  "REDQn",

  "REDKn",



};







  char * reds[max];



  int i;



  FILE * file = argc > 1 ? fopen(argv[1], "r") : stdin;

  if (file == NULL)

    return 1;

  if (argc != 2) {

    printf("[ERR]");

    return 0;

  }



  for (i = 0; i < max; i++) {



    reds[i] = malloc(stringlength);

    fgets(reds[i], stringlength, file);



  }









  for (i = 0; i < max; i++) {



    printf("%s", reds[i]);



  }



  // removes spaces

  for (i = 0; i < max; i++) {

    removechar(reds[i], ' ');





  }



  for (i = 0; i < max; i++) {



    printf("%s", reds[i]);



  }





size_t size = sizeof(stringcard) / sizeof(stringcard[0]);

size_t size2 = sizeof(reds) / sizeof(reds[0]);



all_match(reds,stringcard,size,size2);



for (i = 0; i < max; i++) {



   free(reds[i]);



  }



          return 0;



}   

input:

RED A

RED 2

RED 3

RED 4

RED 5

RED 6

RED 7

RED 8

RED 9

RED 10

RED J

RED Q

RED K

This code works fine as long as the input-file looks like that.

If the input file looks like this:

RED A

RED 2



RED 3

RED 4

RED         5



RED 6

RED 7

RED 8

RED    9

RED 10

RED J



RED Q



RED   K

I get an error. I guess the newlines in between are causing the problem.
Is there anyway to improve my Code?

Undefined behavior

removechar() has problems.

//removes spaces

char * removechar(char str, int ch) {

  char * cpos = str;

  while ((cpos = strchr(cpos, ch))) {

    strcpy(cpos, cpos + 1);

  }

  return str;

}

• It is undefined behavior (UB) to call strcpy() with overlapping strings.




• Inefficient. It algorithm is O(n*n). A string of 100 spaces would take an order of 10,000 operations.




• Comment //removes spaces mis-leads. There is nothing about the function related to a "space", just the attempted removal of some ch which may or may not be a ' '.




• Should code unusually call removechar(str, '') occur, cpos + 1 will point to 1 past the end of the string causing various troubles (UB).

To properly remove matching characters:

char *removechar(char str, int ch) {

  if (ch) {  // if ch == null character, detect that and do not change anything.

    const char *src = str;



    // Optional speedier initial loop should leading characters not contain `ch`

    while (*src && ((unsigned char) *src != (unsigned char) ch)) {

      src++;

    }



    char *dst = str;

    while (*src) {

      if ((unsigned char) *src != (unsigned char) ch) {

        *dst++ = *src;

      }

      src++;

    }

    *dst = '';   

  }

  return str;

}

Note: improved code uses casts in if ((unsigned char) *src != (unsigned char) ch) to cope with ch < 0 or ch > CHAR_MAX and/or char is signed. In such cases the compare intended is likely just the lower bits of *src and ch. strchr(s, c) compares using (unsigned char)*s == (unsigned char). We do likewise.

Alternatively, code could change the signature and drop the casts.

char *removechar(char str, char ch)

Vertical whitespace

For my tastes the vertical spacing is excessive and would benefit with a tidier appearance.

General formatting is weak. Use an auto formatting. Do not fix this manually.

Missing error checking

I'd expect fgets() calls to have their return value checked.

Robust code will check the return value of *alloc()

Error detection sequence

If argc < 2 then fopen(argv[1], "r") is UB. Better to check if (argc != 2) before.

 if (argc != 2) {

    printf("[ERR]");

    return 0;

  }

  FILE * file = argc > 1 ? fopen(argv[1], "r") : stdin;

  if (file == NULL)

    return 1;

  //if (argc != 2) {

  //  printf("[ERR]");

  //  return 0;

  //}

Better for error messages go to stderr.

When file open fails, no message. Consider adding one.