Answers for "c read the file"

read files in c

#include<stdio.h>
int main(){
	FILE *in=fopen("name_of_file.txt","r");
	char c;
	while((c=fgetc(in))!=EOF)
		putchar(c);
	fclose(in);
	return 0;
}

c read file content

char * buffer = 0;
long length;
FILE * f = fopen (filename, "rb");

if (f)
{
  fseek (f, 0, SEEK_END);
  length = ftell (f);
  fseek (f, 0, SEEK_SET);
  buffer = malloc (length);
  if (buffer)
  {
    fread (buffer, 1, length, f);
  }
  fclose (f);
}

if (buffer)
{
  // start to process your data / extract strings here...
}

c read file from command line

You can use as your main function:
int main(int argc, char **argv) 

So, if you entered to run your program:
C:\myprogram myfile.txt

argc will be 2
argv[0] will be myprogram
argv[1] will be myfile.txt

To read the file:
FILE *f = fopen(argv[1], "r");