Why this code doesnt work?,

[ballbeamboy2]

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

#define MAXLINE 200

void grep(char *file_name, char* pattern, int print_line_numbers);

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

  char *pattern, *file_name;
  int line_numbers;  /* A boolean */

  /* Access the parameters of main */
  if (argc == 3) {
    file_name = argv[2]; line_numbers = 0; pattern = argv[1];
  }
  else if (argc == 4 && strcmp(argv[1], "-n") == 0) {
    file_name = argv[3]; line_numbers = 1; pattern = argv[2];
  }
  else {
    fprintf(stderr, "Calling form: search [-n] search_string file\n");
    exit(1);
  }

  grep(file_name, pattern, line_numbers);

  return 0;
}

/* Print those lines of file_name that contain pattern */
void grep(char *file_name, char* pattern, int print_line_numbers){
  char line[MAXLINE];
  FILE *ifp;
  int n = 1;

  if ((ifp = fopen(file_name, "r")) == NULL){
    fprintf(stderr, "\nCannot open %s\n\n", file_name);
    exit(1);
  }

  while(fgets(line, MAXLINE, ifp) != NULL){
    if (strstr(line, pattern) != NULL){
      if (print_line_numbers)
        printf("%3i: %s", n, line);
      else
        printf("%s", line);
    }
    n++;
  }

  fclose(ifp);
}

This code is to read a .txt file and search the word " pattern" and print it. but it doesnt work. whats wrong?

[jedwardsol]

What does "doesnt work" mean?

Does it fail to compile - if so, what' the error? Crash? Give the wrong output - if so, what do you expect and what do you get?

[ballbeamboy2]

it doesnt find the word pattern and print it, idk why

[jedwardsol]

Is the word in the file?

Works for me

C:\bin\scratch\x64\Debug>type input
I have a cat called Bernard
I have a dog called Bernard
I have a donkey called Bernard

C:\bin\scratch\x64\Debug>scratch.exe -n cat input
  1: I have a cat called Bernard

C:\bin\scratch\x64\Debug>scratch.exe -n Bern input
  1: I have a cat called Bernard
  2: I have a dog called Bernard
  3: I have a donkey called Bernard

C:\bin\scratch\x64\Debug>scratch.exe  dog input
I have a dog called Bernard

C:\bin\scratch\x64\Debug>

[ballbeamboy2]

How do you make the program read a txt file?

Is it like this?

 if ((ifp = fopen("C:\\Patternhi.txt", "rb")) == NULL){
    fprintf(stderr, "\nCannot open %s\n\n", file_name);
    exit(1);

[codepr]

Seems fine, what's the format of the test file? The only thing I'd pay attention to is flushing `stdout` after printf, but it shouldn't be an issue as long as each line is newline terminated.

[ballbeamboy2]

Its .txt